convert backtick to repr

IPython/core/debugger.py

@@ -1,525 +1,525
 # -*- coding: utf-8 -*-
 """
 Pdb debugger class.
 
 Modified from the standard pdb.Pdb class to avoid including readline, so that
 the command line completion of other programs which include this isn't
 damaged.
 
 In the future, this class will be expanded with improvements over the standard
 pdb.
 
 The code in this file is mainly lifted out of cmd.py in Python 2.2, with minor
 changes. Licensing should therefore be under the standard Python terms.  For
 details on the PSF (Python Software Foundation) standard license, see:
 
 http://www.python.org/2.2.3/license.html"""
 
 #*****************************************************************************
 #
 #       This file is licensed under the PSF license.
 #
 #       Copyright (C) 2001 Python Software Foundation, www.python.org
 #       Copyright (C) 2005-2006 Fernando Perez. <[e-mail]>
 #
 #
 #*****************************************************************************
 
 import bdb
 import linecache
 import sys
 
 from IPython.utils import PyColorize
 from IPython.core import ipapi
 from IPython.utils import coloransi, io
 from IPython.core.excolors import exception_colors
 
 # See if we can use pydb.
 has_pydb = False
 prompt = 'ipdb> '
 #We have to check this directly from sys.argv, config struct not yet available
 if '--pydb' in sys.argv:
     try:
         import pydb
         if hasattr(pydb.pydb, "runl") and pydb.version>'1.17':
             # Version 1.17 is broken, and that's what ships with Ubuntu Edgy, so we
             # better protect against it.
             has_pydb = True
     except ImportError:
         print "Pydb (http://bashdb.sourceforge.net/pydb/) does not seem to be available"
 
 if has_pydb:
     from pydb import Pdb as OldPdb
     #print "Using pydb for %run -d and post-mortem" #dbg
     prompt = 'ipydb> '
 else:
     from pdb import Pdb as OldPdb
 
 # Allow the set_trace code to operate outside of an ipython instance, even if
 # it does so with some limitations.  The rest of this support is implemented in
 # the Tracer constructor.
 def BdbQuit_excepthook(et,ev,tb):
     if et==bdb.BdbQuit:
         print 'Exiting Debugger.'
     else:
         BdbQuit_excepthook.excepthook_ori(et,ev,tb)
 
 def BdbQuit_IPython_excepthook(self,et,ev,tb,tb_offset=None):
     print 'Exiting Debugger.'
 
 
 class Tracer(object):
     """Class for local debugging, similar to pdb.set_trace.
 
     Instances of this class, when called, behave like pdb.set_trace, but
     providing IPython's enhanced capabilities.
 
     This is implemented as a class which must be initialized in your own code
     and not as a standalone function because we need to detect at runtime
     whether IPython is already active or not.  That detection is done in the
     constructor, ensuring that this code plays nicely with a running IPython,
     while functioning acceptably (though with limitations) if outside of it.
     """
 
     def __init__(self,colors=None):
         """Create a local debugger instance.
 
         :Parameters:
 
           - `colors` (None): a string containing the name of the color scheme to
         use, it must be one of IPython's valid color schemes.  If not given, the
         function will default to the current IPython scheme when running inside
         IPython, and to 'NoColor' otherwise.
 
         Usage example:
 
         from IPython.core.debugger import Tracer; debug_here = Tracer()
 
         ... later in your code
         debug_here()  # -> will open up the debugger at that point.
 
         Once the debugger activates, you can use all of its regular commands to
         step through code, set breakpoints, etc.  See the pdb documentation
         from the Python standard library for usage details.
         """
 
         try:
             ip = get_ipython()
         except NameError:
             # Outside of ipython, we set our own exception hook manually
             BdbQuit_excepthook.excepthook_ori = sys.excepthook
             sys.excepthook = BdbQuit_excepthook
             def_colors = 'NoColor'
             try:
                 # Limited tab completion support
                 import readline
                 readline.parse_and_bind('tab: complete')
             except ImportError:
                 pass
         else:
             # In ipython, we use its custom exception handler mechanism
             def_colors = ip.colors
             ip.set_custom_exc((bdb.BdbQuit,), BdbQuit_IPython_excepthook)
 
         if colors is None:
             colors = def_colors
 
         # The stdlib debugger internally uses a modified repr from the `repr`
         # module, that limits the length of printed strings to a hardcoded
         # limit of 30 characters.  That much trimming is too aggressive, let's
         # at least raise that limit to 80 chars, which should be enough for
         # most interactive uses.
         try:
             from repr import aRepr
             aRepr.maxstring = 80
         except:
             # This is only a user-facing convenience, so any error we encounter
             # here can be warned about but can be otherwise ignored.  These
             # printouts will tell us about problems if this API changes 
             import traceback
             traceback.print_exc()
 
         self.debugger = Pdb(colors)
 
     def __call__(self):
         """Starts an interactive debugger at the point where called.
 
         This is similar to the pdb.set_trace() function from the std lib, but
         using IPython's enhanced debugger."""
 
         self.debugger.set_trace(sys._getframe().f_back)
 
 
 def decorate_fn_with_doc(new_fn, old_fn, additional_text=""):
     """Make new_fn have old_fn's doc string. This is particularly useful
     for the do_... commands that hook into the help system.
     Adapted from from a comp.lang.python posting
     by Duncan Booth."""
     def wrapper(*args, **kw):
         return new_fn(*args, **kw)
     if old_fn.__doc__:
         wrapper.__doc__ = old_fn.__doc__ + additional_text
     return wrapper
 
 
 def _file_lines(fname):
     """Return the contents of a named file as a list of lines.
 
     This function never raises an IOError exception: if the file can't be
     read, it simply returns an empty list."""
 
     try:
         outfile = open(fname)
     except IOError:
         return []
     else:
         out = outfile.readlines()
         outfile.close()
         return out
 
 
 class Pdb(OldPdb):
     """Modified Pdb class, does not load readline."""
 
     def __init__(self,color_scheme='NoColor',completekey=None,
                  stdin=None, stdout=None):
 
         # Parent constructor:
         if has_pydb and completekey is None:
             OldPdb.__init__(self,stdin=stdin,stdout=io.stdout)
         else:
             OldPdb.__init__(self,completekey,stdin,stdout)
 
         self.prompt = prompt # The default prompt is '(Pdb)'
 
         # IPython changes...
         self.is_pydb = has_pydb
 
         self.shell = ipapi.get()
 
         if self.is_pydb:
 
             # interactiveshell.py's ipalias seems to want pdb's checkline
             # which located in pydb.fn
             import pydb.fns
             self.checkline = lambda filename, lineno: \
                              pydb.fns.checkline(self, filename, lineno)
 
             self.curframe = None
             self.do_restart = self.new_do_restart
 
             self.old_all_completions = self.shell.Completer.all_completions
             self.shell.Completer.all_completions=self.all_completions
 
             self.do_list = decorate_fn_with_doc(self.list_command_pydb,
                                                 OldPdb.do_list)
             self.do_l     = self.do_list
             self.do_frame = decorate_fn_with_doc(self.new_do_frame,
                                                  OldPdb.do_frame)
 
         self.aliases = {}
 
         # Create color table: we copy the default one from the traceback
         # module and add a few attributes needed for debugging
         self.color_scheme_table = exception_colors()
 
         # shorthands
         C = coloransi.TermColors
         cst = self.color_scheme_table
 
         cst['NoColor'].colors.breakpoint_enabled = C.NoColor
         cst['NoColor'].colors.breakpoint_disabled = C.NoColor
 
         cst['Linux'].colors.breakpoint_enabled = C.LightRed
         cst['Linux'].colors.breakpoint_disabled = C.Red
 
         cst['LightBG'].colors.breakpoint_enabled = C.LightRed
         cst['LightBG'].colors.breakpoint_disabled = C.Red
 
         self.set_colors(color_scheme)
 
         # Add a python parser so we can syntax highlight source while
         # debugging.
         self.parser = PyColorize.Parser()
 
     def set_colors(self, scheme):
         """Shorthand access to the color table scheme selector method."""
         self.color_scheme_table.set_active_scheme(scheme)
 
     def interaction(self, frame, traceback):
         self.shell.set_completer_frame(frame)
         OldPdb.interaction(self, frame, traceback)
 
     def new_do_up(self, arg):
         OldPdb.do_up(self, arg)
         self.shell.set_completer_frame(self.curframe)
     do_u = do_up = decorate_fn_with_doc(new_do_up, OldPdb.do_up)
 
     def new_do_down(self, arg):
         OldPdb.do_down(self, arg)
         self.shell.set_completer_frame(self.curframe)
 
     do_d = do_down = decorate_fn_with_doc(new_do_down, OldPdb.do_down)
 
     def new_do_frame(self, arg):
         OldPdb.do_frame(self, arg)
         self.shell.set_completer_frame(self.curframe)
 
     def new_do_quit(self, arg):
 
         if hasattr(self, 'old_all_completions'):
             self.shell.Completer.all_completions=self.old_all_completions
 
 
         return OldPdb.do_quit(self, arg)
 
     do_q = do_quit = decorate_fn_with_doc(new_do_quit, OldPdb.do_quit)
 
     def new_do_restart(self, arg):
         """Restart command. In the context of ipython this is exactly the same
         thing as 'quit'."""
         self.msg("Restart doesn't make sense here. Using 'quit' instead.")
         return self.do_quit(arg)
 
     def postloop(self):
         self.shell.set_completer_frame(None)
 
     def print_stack_trace(self):
         try:
             for frame_lineno in self.stack:
                 self.print_stack_entry(frame_lineno, context = 5)
         except KeyboardInterrupt:
             pass
 
     def print_stack_entry(self,frame_lineno,prompt_prefix='\n-> ',
                           context = 3):
         #frame, lineno = frame_lineno
         print >>io.stdout, self.format_stack_entry(frame_lineno, '', context)
 
         # vds: >>
         frame, lineno = frame_lineno
         filename = frame.f_code.co_filename
         self.shell.hooks.synchronize_with_editor(filename, lineno, 0)
         # vds: <<
 
     def format_stack_entry(self, frame_lineno, lprefix=': ', context = 3):
         import linecache, repr
 
         ret = []
 
         Colors = self.color_scheme_table.active_colors
         ColorsNormal = Colors.Normal
         tpl_link = '%s%%s%s' % (Colors.filenameEm, ColorsNormal)
         tpl_call = '%s%%s%s%%s%s' % (Colors.vName, Colors.valEm, ColorsNormal)
         tpl_line = '%%s%s%%s %s%%s' % (Colors.lineno, ColorsNormal)
         tpl_line_em = '%%s%s%%s %s%%s%s' % (Colors.linenoEm, Colors.line,
                                             ColorsNormal)
 
         frame, lineno = frame_lineno
 
         return_value = ''
         if '__return__' in frame.f_locals:
             rv = frame.f_locals['__return__']
             #return_value += '->'
             return_value += repr.repr(rv) + '\n'
         ret.append(return_value)
 
         #s = filename + '(' + `lineno` + ')'
         filename = self.canonic(frame.f_code.co_filename)
         link = tpl_link % filename
 
         if frame.f_code.co_name:
             func = frame.f_code.co_name
         else:
             func = "<lambda>"
 
         call = ''
         if func != '?':
             if '__args__' in frame.f_locals:
                 args = repr.repr(frame.f_locals['__args__'])
             else:
                 args = '()'
             call = tpl_call % (func, args)
 
         # The level info should be generated in the same format pdb uses, to
         # avoid breaking the pdbtrack functionality of python-mode in *emacs.
         if frame is self.curframe:
             ret.append('> ')
         else:
             ret.append('  ')
         ret.append('%s(%s)%s\n' % (link,lineno,call))
 
         start = lineno - 1 - context//2
         lines = linecache.getlines(filename)
         start = max(start, 0)
         start = min(start, len(lines) - context)
         lines = lines[start : start + context]
 
         for i,line in enumerate(lines):
             show_arrow = (start + 1 + i == lineno)
             linetpl = (frame is self.curframe or show_arrow) \
                       and tpl_line_em \
                       or tpl_line
             ret.append(self.__format_line(linetpl, filename,
                                           start + 1 + i, line,
                                           arrow = show_arrow) )
 
         return ''.join(ret)
 
     def __format_line(self, tpl_line, filename, lineno, line, arrow = False):
         bp_mark = ""
         bp_mark_color = ""
 
         scheme = self.color_scheme_table.active_scheme_name
         new_line, err = self.parser.format2(line, 'str', scheme)
         if not err: line = new_line
 
         bp = None
         if lineno in self.get_file_breaks(filename):
             bps = self.get_breaks(filename, lineno)
             bp = bps[-1]
 
         if bp:
             Colors = self.color_scheme_table.active_colors
             bp_mark = str(bp.number)
             bp_mark_color = Colors.breakpoint_enabled
             if not bp.enabled:
                 bp_mark_color = Colors.breakpoint_disabled
 
         numbers_width = 7
         if arrow:
             # This is the line with the error
             pad = numbers_width - len(str(lineno)) - len(bp_mark)
             if pad >= 3:
                 marker = '-'*(pad-3) + '-> '
             elif pad == 2:
                  marker = '> '
             elif pad == 1:
                  marker = '>'
             else:
                  marker = ''
             num = '%s%s' % (marker, str(lineno))
             line = tpl_line % (bp_mark_color + bp_mark, num, line)
         else:
             num = '%*s' % (numbers_width - len(bp_mark), str(lineno))
             line = tpl_line % (bp_mark_color + bp_mark, num, line)
 
         return line
 
     def list_command_pydb(self, arg):
         """List command to use if we have a newer pydb installed"""
         filename, first, last = OldPdb.parse_list_cmd(self, arg)
         if filename is not None:
             self.print_list_lines(filename, first, last)
 
     def print_list_lines(self, filename, first, last):
         """The printing (as opposed to the parsing part of a 'list'
         command."""
         try:
             Colors = self.color_scheme_table.active_colors
             ColorsNormal = Colors.Normal
             tpl_line = '%%s%s%%s %s%%s' % (Colors.lineno, ColorsNormal)
             tpl_line_em = '%%s%s%%s %s%%s%s' % (Colors.linenoEm, Colors.line, ColorsNormal)
             src = []
             for lineno in range(first, last+1):
                 line = linecache.getline(filename, lineno)
                 if not line:
                     break
 
                 if lineno == self.curframe.f_lineno:
                     line = self.__format_line(tpl_line_em, filename, lineno, line, arrow = True)
                 else:
                     line = self.__format_line(tpl_line, filename, lineno, line, arrow = False)
 
                 src.append(line)
                 self.lineno = lineno
 
             print >>io.stdout, ''.join(src)
 
         except KeyboardInterrupt:
             pass
 
     def do_list(self, arg):
         self.lastcmd = 'list'
         last = None
         if arg:
             try:
                 x = eval(arg, {}, {})
                 if type(x) == type(()):
                     first, last = x
                     first = int(first)
                     last = int(last)
                     if last < first:
                         # Assume it's a count
                         last = first + last
                 else:
                     first = max(1, int(x) - 5)
             except:
-                print '*** Error in argument:', `arg`
+                print '*** Error in argument:', repr(arg)
                 return
         elif self.lineno is None:
             first = max(1, self.curframe.f_lineno - 5)
         else:
             first = self.lineno + 1
         if last is None:
             last = first + 10
         self.print_list_lines(self.curframe.f_code.co_filename, first, last)
 
         # vds: >>
         lineno = first
         filename = self.curframe.f_code.co_filename
         self.shell.hooks.synchronize_with_editor(filename, lineno, 0)
         # vds: <<
 
     do_l = do_list
 
     def do_pdef(self, arg):
         """The debugger interface to magic_pdef"""
         namespaces = [('Locals', self.curframe.f_locals),
                       ('Globals', self.curframe.f_globals)]
         self.shell.magic_pdef(arg, namespaces=namespaces)
 
     def do_pdoc(self, arg):
         """The debugger interface to magic_pdoc"""
         namespaces = [('Locals', self.curframe.f_locals),
                       ('Globals', self.curframe.f_globals)]
         self.shell.magic_pdoc(arg, namespaces=namespaces)
 
     def do_pinfo(self, arg):
         """The debugger equivalant of ?obj"""
         namespaces = [('Locals', self.curframe.f_locals),
                       ('Globals', self.curframe.f_globals)]
         self.shell.magic_pinfo("pinfo %s" % arg, namespaces=namespaces)
 
     def checkline(self, filename, lineno):
         """Check whether specified line seems to be executable.
 
         Return `lineno` if it is, 0 if not (e.g. a docstring, comment, blank
         line or EOF). Warning: testing is not comprehensive.
         """
         #######################################################################
         # XXX Hack!  Use python-2.5 compatible code for this call, because with
         # all of our changes, we've drifted from the pdb api in 2.6.  For now,
         # changing:
         #
         #line = linecache.getline(filename, lineno, self.curframe.f_globals)
         # to:
         #
         line = linecache.getline(filename, lineno)
         #
         # does the trick.  But in reality, we need to fix this by reconciling
         # our updates with the new Pdb APIs in Python 2.6.
         #
         # End hack.  The rest of this method is copied verbatim from 2.6 pdb.py
         #######################################################################
 
         if not line:
             print >>self.stdout, 'End of file'
             return 0
         line = line.strip()
         # Don't allow setting breakpoint at a blank line
         if (not line or (line[0] == '#') or
              (line[:3] == '"""') or line[:3] == "'''"):
             print >>self.stdout, '*** Blank or comment'
             return 0
         return lineno

IPython/core/displayhook.py

@@ -1,269 +1,269
 # -*- coding: utf-8 -*-
 """Displayhook for IPython.
 
 This defines a callable class that IPython uses for `sys.displayhook`.
 
 Authors:
 
 * Fernando Perez
 * Brian Granger
 * Robert Kern
 """
 
 #-----------------------------------------------------------------------------
 #       Copyright (C) 2008-2011 The IPython Development Team
 #       Copyright (C) 2001-2007 Fernando Perez <[e-mail]>
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import __builtin__
 
 from IPython.config.configurable import Configurable
 from IPython.utils import io
 from IPython.utils.traitlets import Instance, List
 from IPython.utils.warn import warn
 
 #-----------------------------------------------------------------------------
 # Main displayhook class
 #-----------------------------------------------------------------------------
 
 # TODO: Move the various attributes (cache_size, [others now moved]). Some
 # of these are also attributes of InteractiveShell. They should be on ONE object
 # only and the other objects should ask that one object for their values.
 
 class DisplayHook(Configurable):
     """The custom IPython displayhook to replace sys.displayhook.
 
     This class does many things, but the basic idea is that it is a callable
     that gets called anytime user code returns a value.
     """
 
     shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
 
     def __init__(self, shell=None, cache_size=1000, config=None):
         super(DisplayHook, self).__init__(shell=shell, config=config)
 
         cache_size_min = 3
         if cache_size <= 0:
             self.do_full_cache = 0
             cache_size = 0
         elif cache_size < cache_size_min:
             self.do_full_cache = 0
             cache_size = 0
             warn('caching was disabled (min value for cache size is %s).' %
                  cache_size_min,level=3)
         else:
             self.do_full_cache = 1
 
         self.cache_size = cache_size
 
         # we need a reference to the user-level namespace
         self.shell = shell
         
         self._,self.__,self.___ = '','',''
 
         # these are deliberately global:
         to_user_ns = {'_':self._,'__':self.__,'___':self.___}
         self.shell.user_ns.update(to_user_ns)
 
     @property
     def prompt_count(self):
         return self.shell.execution_count
 
     #-------------------------------------------------------------------------
     # Methods used in __call__. Override these methods to modify the behavior
     # of the displayhook.
     #-------------------------------------------------------------------------
 
     def check_for_underscore(self):
         """Check if the user has set the '_' variable by hand."""
         # If something injected a '_' variable in __builtin__, delete
         # ipython's automatic one so we don't clobber that.  gettext() in
         # particular uses _, so we need to stay away from it.
         if '_' in __builtin__.__dict__:
             try:
                 del self.shell.user_ns['_']
             except KeyError:
                 pass
 
     def quiet(self):
         """Should we silence the display hook because of ';'?"""
         # do not print output if input ends in ';'
         try:
             cell = self.shell.history_manager.input_hist_parsed[self.prompt_count]
             if cell.rstrip().endswith(';'):
                 return True
         except IndexError:
             # some uses of ipshellembed may fail here
             pass
         return False
 
     def start_displayhook(self):
         """Start the displayhook, initializing resources."""
         pass
 
     def write_output_prompt(self):
         """Write the output prompt.
 
         The default implementation simply writes the prompt to
         ``io.stdout``.
         """
         # Use write, not print which adds an extra space.
         io.stdout.write(self.shell.separate_out)
         outprompt = self.shell.prompt_manager.render('out')
         if self.do_full_cache:
             io.stdout.write(outprompt)
 
     def compute_format_data(self, result):
         """Compute format data of the object to be displayed.
 
         The format data is a generalization of the :func:`repr` of an object.
         In the default implementation the format data is a :class:`dict` of
         key value pair where the keys are valid MIME types and the values
         are JSON'able data structure containing the raw data for that MIME
         type. It is up to frontends to determine pick a MIME to to use and
         display that data in an appropriate manner.
 
         This method only computes the format data for the object and should
         NOT actually print or write that to a stream.
 
         Parameters
         ----------
         result : object
             The Python object passed to the display hook, whose format will be
             computed.
 
         Returns
         -------
         format_data : dict
             A :class:`dict` whose keys are valid MIME types and values are
             JSON'able raw data for that MIME type. It is recommended that
             all return values of this should always include the "text/plain"
             MIME type representation of the object.
         """
         return self.shell.display_formatter.format(result)
 
     def write_format_data(self, format_dict):
         """Write the format data dict to the frontend.
 
         This default version of this method simply writes the plain text
         representation of the object to ``io.stdout``. Subclasses should
         override this method to send the entire `format_dict` to the
         frontends.
 
         Parameters
         ----------
         format_dict : dict
             The format dict for the object passed to `sys.displayhook`.
         """
         # We want to print because we want to always make sure we have a
         # newline, even if all the prompt separators are ''. This is the
         # standard IPython behavior.
         result_repr = format_dict['text/plain']
         if '\n' in result_repr:
             # So that multi-line strings line up with the left column of
             # the screen, instead of having the output prompt mess up
             # their first line.
             # We use the prompt template instead of the expanded prompt
             # because the expansion may add ANSI escapes that will interfere
             # with our ability to determine whether or not we should add
             # a newline.
             prompt_template = self.shell.prompt_manager.out_template
             if prompt_template and not prompt_template.endswith('\n'):
                 # But avoid extraneous empty lines.
                 result_repr = '\n' + result_repr
 
         print >>io.stdout, result_repr
 
     def update_user_ns(self, result):
         """Update user_ns with various things like _, __, _1, etc."""
 
         # Avoid recursive reference when displaying _oh/Out
         if result is not self.shell.user_ns['_oh']:
             if len(self.shell.user_ns['_oh']) >= self.cache_size and self.do_full_cache:
                 warn('Output cache limit (currently '+
-                      `self.cache_size`+' entries) hit.\n'
+                      repr(self.cache_size)+' entries) hit.\n'
                      'Flushing cache and resetting history counter...\n'
                      'The only history variables available will be _,__,___ and _1\n'
                      'with the current result.')
 
                 self.flush()
             # Don't overwrite '_' and friends if '_' is in __builtin__ (otherwise
             # we cause buggy behavior for things like gettext).
 
             if '_' not in __builtin__.__dict__:
                 self.___ = self.__
                 self.__ = self._
                 self._ = result
                 self.shell.push({'_':self._,
                                  '__':self.__,
                                 '___':self.___}, interactive=False)
 
             # hackish access to top-level  namespace to create _1,_2... dynamically
             to_main = {}
             if self.do_full_cache:
-                new_result = '_'+`self.prompt_count`
+                new_result = '_'+repr(self.prompt_count)
                 to_main[new_result] = result
                 self.shell.push(to_main, interactive=False)
                 self.shell.user_ns['_oh'][self.prompt_count] = result
 
     def log_output(self, format_dict):
         """Log the output."""
         if self.shell.logger.log_output:
             self.shell.logger.log_write(format_dict['text/plain'], 'output')
         self.shell.history_manager.output_hist_reprs[self.prompt_count] = \
                                                     format_dict['text/plain']
 
     def finish_displayhook(self):
         """Finish up all displayhook activities."""
         io.stdout.write(self.shell.separate_out2)
         io.stdout.flush()
 
     def __call__(self, result=None):
         """Printing with history cache management.
 
         This is invoked everytime the interpreter needs to print, and is
         activated by setting the variable sys.displayhook to it.
         """
         self.check_for_underscore()
         if result is not None and not self.quiet():
             self.start_displayhook()
             self.write_output_prompt()
             format_dict = self.compute_format_data(result)
             self.write_format_data(format_dict)
             self.update_user_ns(result)
             self.log_output(format_dict)
             self.finish_displayhook()
 
     def flush(self):
         if not self.do_full_cache:
             raise ValueError,"You shouldn't have reached the cache flush "\
                   "if full caching is not enabled!"
         # delete auto-generated vars from global namespace
 
         for n in range(1,self.prompt_count + 1):
-            key = '_'+`n`
+            key = '_'+repr(n)
             try:
                 del self.shell.user_ns[key]
             except: pass
         # In some embedded circumstances, the user_ns doesn't have the
         # '_oh' key set up.
         oh = self.shell.user_ns.get('_oh', None)
         if oh is not None:
             oh.clear()
 
         # Release our own references to objects:
         self._, self.__, self.___ = '', '', ''
 
         if '_' not in __builtin__.__dict__:
             self.shell.user_ns.update({'_':None,'__':None, '___':None})
         import gc
         # TODO: Is this really needed?
         gc.collect()
 

IPython/core/logger.py

@@ -1,220 +1,220
 """Logger class for IPython's logging facilities.
 """
 
 #*****************************************************************************
 #       Copyright (C) 2001 Janko Hauser <[e-mail]> and
 #       Copyright (C) 2001-2006 Fernando Perez <[e-mail]>
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #*****************************************************************************
 
 #****************************************************************************
 # Modules and globals
 
 # Python standard modules
 import glob
 import io
 import os
 import time
 
 from IPython.utils.py3compat import str_to_unicode
 
 #****************************************************************************
 # FIXME: This class isn't a mixin anymore, but it still needs attributes from
 # ipython and does input cache management.  Finish cleanup later...
 
 class Logger(object):
     """A Logfile class with different policies for file creation"""
 
     def __init__(self, home_dir, logfname='Logger.log', loghead=u'',
                  logmode='over'):
 
         # this is the full ipython instance, we need some attributes from it
         # which won't exist until later. What a mess, clean up later...
         self.home_dir = home_dir
 
         self.logfname = logfname
         self.loghead = loghead
         self.logmode = logmode
         self.logfile = None
 
         # Whether to log raw or processed input
         self.log_raw_input = False
 
         # whether to also log output
         self.log_output = False
 
         # whether to put timestamps before each log entry
         self.timestamp = False
 
         # activity control flags
         self.log_active = False
 
     # logmode is a validated property
     def _set_mode(self,mode):
         if mode not in ['append','backup','global','over','rotate']:
             raise ValueError,'invalid log mode %s given' % mode
         self._logmode = mode
 
     def _get_mode(self):
         return self._logmode
 
     logmode = property(_get_mode,_set_mode)
 
     def logstart(self, logfname=None, loghead=None, logmode=None,
                  log_output=False, timestamp=False, log_raw_input=False):
         """Generate a new log-file with a default header.
 
         Raises RuntimeError if the log has already been started"""
 
         if self.logfile is not None:
             raise RuntimeError('Log file is already active: %s' %
                                self.logfname)
 
         # The parameters can override constructor defaults
         if logfname is not None: self.logfname = logfname
         if loghead is not None: self.loghead = loghead
         if logmode is not None: self.logmode = logmode
 
         # Parameters not part of the constructor
         self.timestamp = timestamp
         self.log_output = log_output
         self.log_raw_input = log_raw_input
 
         # init depending on the log mode requested
         isfile = os.path.isfile
         logmode = self.logmode
 
         if logmode == 'append':
             self.logfile = io.open(self.logfname, 'a', encoding='utf-8')
 
         elif logmode == 'backup':
             if isfile(self.logfname):
                 backup_logname = self.logfname+'~'
                 # Manually remove any old backup, since os.rename may fail
                 # under Windows.
                 if isfile(backup_logname):
                     os.remove(backup_logname)
                 os.rename(self.logfname,backup_logname)
             self.logfile = io.open(self.logfname, 'w', encoding='utf-8')
 
         elif logmode == 'global':
             self.logfname = os.path.join(self.home_dir,self.logfname)
             self.logfile = io.open(self.logfname, 'a', encoding='utf-8')
 
         elif logmode == 'over':
             if isfile(self.logfname):
                 os.remove(self.logfname)
             self.logfile = io.open(self.logfname,'w', encoding='utf-8')
 
         elif logmode == 'rotate':
             if isfile(self.logfname):
                 if isfile(self.logfname+'.001~'):
                     old = glob.glob(self.logfname+'.*~')
                     old.sort()
                     old.reverse()
                     for f in old:
                         root, ext = os.path.splitext(f)
                         num = int(ext[1:-1])+1
-                        os.rename(f, root+'.'+`num`.zfill(3)+'~')
+                        os.rename(f, root+'.'+repr(num).zfill(3)+'~')
                 os.rename(self.logfname, self.logfname+'.001~')
             self.logfile = io.open(self.logfname, 'w', encoding='utf-8')
 
         if logmode != 'append':
             self.logfile.write(self.loghead)
 
         self.logfile.flush()
         self.log_active = True
 
     def switch_log(self,val):
         """Switch logging on/off. val should be ONLY a boolean."""
 
         if val not in [False,True,0,1]:
             raise ValueError, \
                   'Call switch_log ONLY with a boolean argument, not with:',val
 
         label = {0:'OFF',1:'ON',False:'OFF',True:'ON'}
 
         if self.logfile is None:
             print """
 Logging hasn't been started yet (use logstart for that).
 
 %logon/%logoff are for temporarily starting and stopping logging for a logfile
 which already exists. But you must first start the logging process with
 %logstart (optionally giving a logfile name)."""
 
         else:
             if self.log_active == val:
                 print 'Logging is already',label[val]
             else:
                 print 'Switching logging',label[val]
                 self.log_active = not self.log_active
                 self.log_active_out = self.log_active
 
     def logstate(self):
         """Print a status message about the logger."""
         if self.logfile is None:
             print 'Logging has not been activated.'
         else:
             state = self.log_active and 'active' or 'temporarily suspended'
             print 'Filename       :',self.logfname
             print 'Mode           :',self.logmode
             print 'Output logging :',self.log_output
             print 'Raw input log  :',self.log_raw_input
             print 'Timestamping   :',self.timestamp
             print 'State          :',state
 
     def log(self, line_mod, line_ori):
         """Write the sources to a log.
 
         Inputs:
 
         - line_mod: possibly modified input, such as the transformations made
         by input prefilters or input handlers of various kinds.  This should
         always be valid Python.
 
         - line_ori: unmodified input line from the user.  This is not
         necessarily valid Python.
         """
 
         # Write the log line, but decide which one according to the
         # log_raw_input flag, set when the log is started.
         if self.log_raw_input:
             self.log_write(line_ori)
         else:
             self.log_write(line_mod)
 
     def log_write(self, data, kind='input'):
         """Write data to the log file, if active"""
 
         #print 'data: %r' % data # dbg
         if self.log_active and data:
             write = self.logfile.write
             if kind=='input':
                 if self.timestamp:
                     write(str_to_unicode(time.strftime('# %a, %d %b %Y %H:%M:%S\n',
                                         time.localtime())))
                 write(data)
             elif kind=='output' and self.log_output:
                 odata = u'\n'.join([u'#[Out]# %s' % s
                                    for s in data.splitlines()])
                 write(u'%s\n' % odata)
             self.logfile.flush()
 
     def logstop(self):
         """Fully stop logging and close log file.
 
         In order to start logging again, a new logstart() call needs to be
         made, possibly (though not necessarily) with a new filename, mode and
         other options."""
 
         if self.logfile is not None:
             self.logfile.close()
             self.logfile = None
         else:
             print "Logging hadn't been started."
         self.log_active = False
 
     # For backwards compatibility, in case anyone was using this.
     close_log = logstop

IPython/core/magics/execution.py

@@ -1,1022 +1,1022
 """Implementation of execution-related magic functions.
 """
 #-----------------------------------------------------------------------------
 #  Copyright (c) 2012 The IPython Development Team.
 #
 #  Distributed under the terms of the Modified BSD License.
 #
 #  The full license is in the file COPYING.txt, distributed with this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 # Stdlib
 import __builtin__ as builtin_mod
 import bdb
 import os
 import sys
 import time
 from StringIO import StringIO
 
 # cProfile was added in Python2.5
 try:
     import cProfile as profile
     import pstats
 except ImportError:
     # profile isn't bundled by default in Debian for license reasons
     try:
         import profile, pstats
     except ImportError:
         profile = pstats = None
 
 # Our own packages
 from IPython.core import debugger, oinspect
 from IPython.core import magic_arguments
 from IPython.core import page
 from IPython.core.error import UsageError
 from IPython.core.macro import Macro
 from IPython.core.magic import (Magics, magics_class, line_magic, cell_magic,
                                 line_cell_magic, on_off, needs_local_scope)
 from IPython.testing.skipdoctest import skip_doctest
 from IPython.utils import py3compat
 from IPython.utils.io import capture_output
 from IPython.utils.ipstruct import Struct
 from IPython.utils.module_paths import find_mod
 from IPython.utils.path import get_py_filename, unquote_filename
 from IPython.utils.timing import clock, clock2
 from IPython.utils.warn import warn, error
 
 #-----------------------------------------------------------------------------
 # Magic implementation classes
 #-----------------------------------------------------------------------------
 
 @magics_class
 class ExecutionMagics(Magics):
     """Magics related to code execution, debugging, profiling, etc.
 
     """
 
     def __init__(self, shell):
         super(ExecutionMagics, self).__init__(shell)
         if profile is None:
             self.prun = self.profile_missing_notice
         # Default execution function used to actually run user code.
         self.default_runner = None
 
     def profile_missing_notice(self, *args, **kwargs):
         error("""\
 The profile module could not be found. It has been removed from the standard
 python packages because of its non-free license. To use profiling, install the
 python-profiler package from non-free.""")
 
     @skip_doctest
     @line_cell_magic
     def prun(self, parameter_s='', cell=None, user_mode=True,
                    opts=None,arg_lst=None,prog_ns=None):
 
         """Run a statement through the python code profiler.
 
         Usage, in line mode:
           %prun [options] statement
 
         Usage, in cell mode:
           %%prun [options] [statement]
           code...
           code...
 
         In cell mode, the additional code lines are appended to the (possibly
         empty) statement in the first line.  Cell mode allows you to easily
         profile multiline blocks without having to put them in a separate
         function.
         
         The given statement (which doesn't require quote marks) is run via the
         python profiler in a manner similar to the profile.run() function.
         Namespaces are internally managed to work correctly; profile.run
         cannot be used in IPython because it makes certain assumptions about
         namespaces which do not hold under IPython.
 
         Options:
 
         -l <limit>: you can place restrictions on what or how much of the
         profile gets printed. The limit value can be:
 
           * A string: only information for function names containing this string
           is printed.
 
           * An integer: only these many lines are printed.
 
           * A float (between 0 and 1): this fraction of the report is printed
           (for example, use a limit of 0.4 to see the topmost 40% only).
 
         You can combine several limits with repeated use of the option. For
         example, '-l __init__ -l 5' will print only the topmost 5 lines of
         information about class constructors.
 
         -r: return the pstats.Stats object generated by the profiling. This
         object has all the information about the profile in it, and you can
         later use it for further analysis or in other functions.
 
        -s <key>: sort profile by given key. You can provide more than one key
         by using the option several times: '-s key1 -s key2 -s key3...'. The
         default sorting key is 'time'.
 
         The following is copied verbatim from the profile documentation
         referenced below:
 
         When more than one key is provided, additional keys are used as
         secondary criteria when the there is equality in all keys selected
         before them.
 
         Abbreviations can be used for any key names, as long as the
         abbreviation is unambiguous.  The following are the keys currently
         defined:
 
                 Valid Arg       Meaning
                   "calls"      call count
                   "cumulative" cumulative time
                   "file"       file name
                   "module"     file name
                   "pcalls"     primitive call count
                   "line"       line number
                   "name"       function name
                   "nfl"        name/file/line
                   "stdname"    standard name
                   "time"       internal time
 
         Note that all sorts on statistics are in descending order (placing
         most time consuming items first), where as name, file, and line number
         searches are in ascending order (i.e., alphabetical). The subtle
         distinction between "nfl" and "stdname" is that the standard name is a
         sort of the name as printed, which means that the embedded line
         numbers get compared in an odd way.  For example, lines 3, 20, and 40
         would (if the file names were the same) appear in the string order
         "20" "3" and "40".  In contrast, "nfl" does a numeric compare of the
         line numbers.  In fact, sort_stats("nfl") is the same as
         sort_stats("name", "file", "line").
 
         -T <filename>: save profile results as shown on screen to a text
         file. The profile is still shown on screen.
 
         -D <filename>: save (via dump_stats) profile statistics to given
         filename. This data is in a format understood by the pstats module, and
         is generated by a call to the dump_stats() method of profile
         objects. The profile is still shown on screen.
 
         -q: suppress output to the pager.  Best used with -T and/or -D above.
 
         If you want to run complete programs under the profiler's control, use
         '%run -p [prof_opts] filename.py [args to program]' where prof_opts
         contains profiler specific options as described here.
 
         You can read the complete documentation for the profile module with::
 
           In [1]: import profile; profile.help()
         """
 
         opts_def = Struct(D=[''],l=[],s=['time'],T=[''])
 
         if user_mode:  # regular user call
             opts,arg_str = self.parse_options(parameter_s,'D:l:rs:T:q',
                                               list_all=True, posix=False)
             namespace = self.shell.user_ns
             if cell is not None:
                 arg_str += '\n' + cell
         else:  # called to run a program by %run -p
             try:
                 filename = get_py_filename(arg_lst[0])
             except IOError as e:
                 try:
                     msg = str(e)
                 except UnicodeError:
                     msg = e.message
                 error(msg)
                 return
 
             arg_str = 'execfile(filename,prog_ns)'
             namespace = {
                 'execfile': self.shell.safe_execfile,
                 'prog_ns': prog_ns,
                 'filename': filename
                 }
 
         opts.merge(opts_def)
 
         prof = profile.Profile()
         try:
             prof = prof.runctx(arg_str,namespace,namespace)
             sys_exit = ''
         except SystemExit:
             sys_exit = """*** SystemExit exception caught in code being profiled."""
 
         stats = pstats.Stats(prof).strip_dirs().sort_stats(*opts.s)
 
         lims = opts.l
         if lims:
             lims = []  # rebuild lims with ints/floats/strings
             for lim in opts.l:
                 try:
                     lims.append(int(lim))
                 except ValueError:
                     try:
                         lims.append(float(lim))
                     except ValueError:
                         lims.append(lim)
 
         # Trap output.
         stdout_trap = StringIO()
 
         if hasattr(stats,'stream'):
             # In newer versions of python, the stats object has a 'stream'
             # attribute to write into.
             stats.stream = stdout_trap
             stats.print_stats(*lims)
         else:
             # For older versions, we manually redirect stdout during printing
             sys_stdout = sys.stdout
             try:
                 sys.stdout = stdout_trap
                 stats.print_stats(*lims)
             finally:
                 sys.stdout = sys_stdout
 
         output = stdout_trap.getvalue()
         output = output.rstrip()
 
         if 'q' not in opts:
             page.page(output)
         print sys_exit,
 
         dump_file = opts.D[0]
         text_file = opts.T[0]
         if dump_file:
             dump_file = unquote_filename(dump_file)
             prof.dump_stats(dump_file)
             print '\n*** Profile stats marshalled to file',\
-                  `dump_file`+'.',sys_exit
+                  repr(dump_file)+'.',sys_exit
         if text_file:
             text_file = unquote_filename(text_file)
             pfile = open(text_file,'w')
             pfile.write(output)
             pfile.close()
             print '\n*** Profile printout saved to text file',\
-                  `text_file`+'.',sys_exit
+                  repr(text_file)+'.',sys_exit
 
         if opts.has_key('r'):
             return stats
         else:
             return None
 
     @line_magic
     def pdb(self, parameter_s=''):
         """Control the automatic calling of the pdb interactive debugger.
 
         Call as '%pdb on', '%pdb 1', '%pdb off' or '%pdb 0'. If called without
         argument it works as a toggle.
 
         When an exception is triggered, IPython can optionally call the
         interactive pdb debugger after the traceback printout. %pdb toggles
         this feature on and off.
 
         The initial state of this feature is set in your configuration
         file (the option is ``InteractiveShell.pdb``).
 
         If you want to just activate the debugger AFTER an exception has fired,
         without having to type '%pdb on' and rerunning your code, you can use
         the %debug magic."""
 
         par = parameter_s.strip().lower()
 
         if par:
             try:
                 new_pdb = {'off':0,'0':0,'on':1,'1':1}[par]
             except KeyError:
                 print ('Incorrect argument. Use on/1, off/0, '
                        'or nothing for a toggle.')
                 return
         else:
             # toggle
             new_pdb = not self.shell.call_pdb
 
         # set on the shell
         self.shell.call_pdb = new_pdb
         print 'Automatic pdb calling has been turned',on_off(new_pdb)
 
     @line_magic
     def debug(self, parameter_s=''):
         """Activate the interactive debugger in post-mortem mode.
 
         If an exception has just occurred, this lets you inspect its stack
         frames interactively.  Note that this will always work only on the last
         traceback that occurred, so you must call this quickly after an
         exception that you wish to inspect has fired, because if another one
         occurs, it clobbers the previous one.
 
         If you want IPython to automatically do this on every exception, see
         the %pdb magic for more details.
         """
         self.shell.debugger(force=True)
 
     @line_magic
     def tb(self, s):
         """Print the last traceback with the currently active exception mode.
 
         See %xmode for changing exception reporting modes."""
         self.shell.showtraceback()
 
     @skip_doctest
     @line_magic
     def run(self, parameter_s='', runner=None,
                   file_finder=get_py_filename):
         """Run the named file inside IPython as a program.
 
         Usage:\\
           %run [-n -i -t [-N<N>] -d [-b<N>] -p [profile options]] file [args]
 
         Parameters after the filename are passed as command-line arguments to
         the program (put in sys.argv). Then, control returns to IPython's
         prompt.
 
         This is similar to running at a system prompt:\\
           $ python file args\\
         but with the advantage of giving you IPython's tracebacks, and of
         loading all variables into your interactive namespace for further use
         (unless -p is used, see below).
 
         The file is executed in a namespace initially consisting only of
         __name__=='__main__' and sys.argv constructed as indicated. It thus
         sees its environment as if it were being run as a stand-alone program
         (except for sharing global objects such as previously imported
         modules). But after execution, the IPython interactive namespace gets
         updated with all variables defined in the program (except for __name__
         and sys.argv). This allows for very convenient loading of code for
         interactive work, while giving each program a 'clean sheet' to run in.
 
         Options:
 
         -n: __name__ is NOT set to '__main__', but to the running file's name
         without extension (as python does under import).  This allows running
         scripts and reloading the definitions in them without calling code
         protected by an ' if __name__ == "__main__" ' clause.
 
         -i: run the file in IPython's namespace instead of an empty one. This
         is useful if you are experimenting with code written in a text editor
         which depends on variables defined interactively.
 
         -e: ignore sys.exit() calls or SystemExit exceptions in the script
         being run.  This is particularly useful if IPython is being used to
         run unittests, which always exit with a sys.exit() call.  In such
         cases you are interested in the output of the test results, not in
         seeing a traceback of the unittest module.
 
         -t: print timing information at the end of the run.  IPython will give
         you an estimated CPU time consumption for your script, which under
         Unix uses the resource module to avoid the wraparound problems of
         time.clock().  Under Unix, an estimate of time spent on system tasks
         is also given (for Windows platforms this is reported as 0.0).
 
         If -t is given, an additional -N<N> option can be given, where <N>
         must be an integer indicating how many times you want the script to
         run.  The final timing report will include total and per run results.
 
         For example (testing the script uniq_stable.py)::
 
             In [1]: run -t uniq_stable
 
             IPython CPU timings (estimated):\\
               User  :    0.19597 s.\\
               System:        0.0 s.\\
 
             In [2]: run -t -N5 uniq_stable
 
             IPython CPU timings (estimated):\\
             Total runs performed: 5\\
               Times :      Total       Per run\\
               User  :   0.910862 s,  0.1821724 s.\\
               System:        0.0 s,        0.0 s.
 
         -d: run your program under the control of pdb, the Python debugger.
         This allows you to execute your program step by step, watch variables,
         etc.  Internally, what IPython does is similar to calling:
 
           pdb.run('execfile("YOURFILENAME")')
 
         with a breakpoint set on line 1 of your file.  You can change the line
         number for this automatic breakpoint to be <N> by using the -bN option
         (where N must be an integer).  For example::
 
           %run -d -b40 myscript
 
         will set the first breakpoint at line 40 in myscript.py.  Note that
         the first breakpoint must be set on a line which actually does
         something (not a comment or docstring) for it to stop execution.
 
         When the pdb debugger starts, you will see a (Pdb) prompt.  You must
         first enter 'c' (without quotes) to start execution up to the first
         breakpoint.
 
         Entering 'help' gives information about the use of the debugger.  You
         can easily see pdb's full documentation with "import pdb;pdb.help()"
         at a prompt.
 
         -p: run program under the control of the Python profiler module (which
         prints a detailed report of execution times, function calls, etc).
 
         You can pass other options after -p which affect the behavior of the
         profiler itself. See the docs for %prun for details.
 
         In this mode, the program's variables do NOT propagate back to the
         IPython interactive namespace (because they remain in the namespace
         where the profiler executes them).
 
         Internally this triggers a call to %prun, see its documentation for
         details on the options available specifically for profiling.
 
         There is one special usage for which the text above doesn't apply:
         if the filename ends with .ipy, the file is run as ipython script,
         just as if the commands were written on IPython prompt.
 
         -m: specify module name to load instead of script path. Similar to
         the -m option for the python interpreter. Use this option last if you
         want to combine with other %run options. Unlike the python interpreter
         only source modules are allowed no .pyc or .pyo files.
         For example::
 
             %run -m example
 
         will run the example module.
 
         """
 
         # get arguments and set sys.argv for program to be run.
         opts, arg_lst = self.parse_options(parameter_s, 'nidtN:b:pD:l:rs:T:em:',
                                            mode='list', list_all=1)
         if "m" in opts:
             modulename = opts["m"][0]
             modpath = find_mod(modulename)
             if modpath is None:
                 warn('%r is not a valid modulename on sys.path'%modulename)
                 return
             arg_lst = [modpath] + arg_lst
         try:
             filename = file_finder(arg_lst[0])
         except IndexError:
             warn('you must provide at least a filename.')
             print '\n%run:\n', oinspect.getdoc(self.run)
             return
         except IOError as e:
             try:
                 msg = str(e)
             except UnicodeError:
                 msg = e.message
             error(msg)
             return
 
         if filename.lower().endswith('.ipy'):
             self.shell.safe_execfile_ipy(filename)
             return
 
         # Control the response to exit() calls made by the script being run
         exit_ignore = 'e' in opts
 
         # Make sure that the running script gets a proper sys.argv as if it
         # were run from a system shell.
         save_argv = sys.argv # save it for later restoring
 
         # simulate shell expansion on arguments, at least tilde expansion
         args = [ os.path.expanduser(a) for a in arg_lst[1:] ]
 
         sys.argv = [filename] + args  # put in the proper filename
         # protect sys.argv from potential unicode strings on Python 2:
         if not py3compat.PY3:
             sys.argv = [ py3compat.cast_bytes(a) for a in sys.argv ]
 
         if 'i' in opts:
             # Run in user's interactive namespace
             prog_ns = self.shell.user_ns
             __name__save = self.shell.user_ns['__name__']
             prog_ns['__name__'] = '__main__'
             main_mod = self.shell.new_main_mod(prog_ns)
         else:
             # Run in a fresh, empty namespace
             if 'n' in opts:
                 name = os.path.splitext(os.path.basename(filename))[0]
             else:
                 name = '__main__'
 
             main_mod = self.shell.new_main_mod()
             prog_ns = main_mod.__dict__
             prog_ns['__name__'] = name
 
         # Since '%run foo' emulates 'python foo.py' at the cmd line, we must
         # set the __file__ global in the script's namespace
         prog_ns['__file__'] = filename
 
         # pickle fix.  See interactiveshell for an explanation.  But we need to
         # make sure that, if we overwrite __main__, we replace it at the end
         main_mod_name = prog_ns['__name__']
 
         if main_mod_name == '__main__':
             restore_main = sys.modules['__main__']
         else:
             restore_main = False
 
         # This needs to be undone at the end to prevent holding references to
         # every single object ever created.
         sys.modules[main_mod_name] = main_mod
 
         try:
             stats = None
             with self.shell.readline_no_record:
                 if 'p' in opts:
                     stats = self.prun('', None, False, opts, arg_lst, prog_ns)
                 else:
                     if 'd' in opts:
                         deb = debugger.Pdb(self.shell.colors)
                         # reset Breakpoint state, which is moronically kept
                         # in a class
                         bdb.Breakpoint.next = 1
                         bdb.Breakpoint.bplist = {}
                         bdb.Breakpoint.bpbynumber = [None]
                         # Set an initial breakpoint to stop execution
                         maxtries = 10
                         bp = int(opts.get('b', [1])[0])
                         checkline = deb.checkline(filename, bp)
                         if not checkline:
                             for bp in range(bp + 1, bp + maxtries + 1):
                                 if deb.checkline(filename, bp):
                                     break
                             else:
                                 msg = ("\nI failed to find a valid line to set "
                                        "a breakpoint\n"
                                        "after trying up to line: %s.\n"
                                        "Please set a valid breakpoint manually "
                                        "with the -b option." % bp)
                                 error(msg)
                                 return
                         # if we find a good linenumber, set the breakpoint
                         deb.do_break('%s:%s' % (filename, bp))
                         # Start file run
                         print "NOTE: Enter 'c' at the",
                         print "%s prompt to start your script." % deb.prompt
                         ns = {'execfile': py3compat.execfile, 'prog_ns': prog_ns}
                         try:
                             deb.run('execfile("%s", prog_ns)' % filename, ns)
 
                         except:
                             etype, value, tb = sys.exc_info()
                             # Skip three frames in the traceback: the %run one,
                             # one inside bdb.py, and the command-line typed by the
                             # user (run by exec in pdb itself).
                             self.shell.InteractiveTB(etype, value, tb, tb_offset=3)
                     else:
                         if runner is None:
                             runner = self.default_runner
                         if runner is None:
                             runner = self.shell.safe_execfile
                         if 't' in opts:
                             # timed execution
                             try:
                                 nruns = int(opts['N'][0])
                                 if nruns < 1:
                                     error('Number of runs must be >=1')
                                     return
                             except (KeyError):
                                 nruns = 1
                             twall0 = time.time()
                             if nruns == 1:
                                 t0 = clock2()
                                 runner(filename, prog_ns, prog_ns,
                                        exit_ignore=exit_ignore)
                                 t1 = clock2()
                                 t_usr = t1[0] - t0[0]
                                 t_sys = t1[1] - t0[1]
                                 print "\nIPython CPU timings (estimated):"
                                 print "  User   : %10.2f s." % t_usr
                                 print "  System : %10.2f s." % t_sys
                             else:
                                 runs = range(nruns)
                                 t0 = clock2()
                                 for nr in runs:
                                     runner(filename, prog_ns, prog_ns,
                                            exit_ignore=exit_ignore)
                                 t1 = clock2()
                                 t_usr = t1[0] - t0[0]
                                 t_sys = t1[1] - t0[1]
                                 print "\nIPython CPU timings (estimated):"
                                 print "Total runs performed:", nruns
                                 print "  Times  : %10.2f    %10.2f" % ('Total', 'Per run')
                                 print "  User   : %10.2f s, %10.2f s." % (t_usr, t_usr / nruns)
                                 print "  System : %10.2f s, %10.2f s." % (t_sys, t_sys / nruns)
                             twall1 = time.time()
                             print "Wall time: %10.2f s." % (twall1 - twall0)
 
                         else:
                             # regular execution
                             runner(filename, prog_ns, prog_ns, exit_ignore=exit_ignore)
 
                 if 'i' in opts:
                     self.shell.user_ns['__name__'] = __name__save
                 else:
                     # The shell MUST hold a reference to prog_ns so after %run
                     # exits, the python deletion mechanism doesn't zero it out
                     # (leaving dangling references).
                     self.shell.cache_main_mod(prog_ns, filename)
                     # update IPython interactive namespace
 
                     # Some forms of read errors on the file may mean the
                     # __name__ key was never set; using pop we don't have to
                     # worry about a possible KeyError.
                     prog_ns.pop('__name__', None)
 
                     self.shell.user_ns.update(prog_ns)
         finally:
             # It's a bit of a mystery why, but __builtins__ can change from
             # being a module to becoming a dict missing some key data after
             # %run.  As best I can see, this is NOT something IPython is doing
             # at all, and similar problems have been reported before:
             # http://coding.derkeiler.com/Archive/Python/comp.lang.python/2004-10/0188.html
             # Since this seems to be done by the interpreter itself, the best
             # we can do is to at least restore __builtins__ for the user on
             # exit.
             self.shell.user_ns['__builtins__'] = builtin_mod
 
             # Ensure key global structures are restored
             sys.argv = save_argv
             if restore_main:
                 sys.modules['__main__'] = restore_main
             else:
                 # Remove from sys.modules the reference to main_mod we'd
                 # added.  Otherwise it will trap references to objects
                 # contained therein.
                 del sys.modules[main_mod_name]
 
         return stats
 
     @skip_doctest
     @line_cell_magic
     def timeit(self, line='', cell=None):
         """Time execution of a Python statement or expression
 
         Usage, in line mode:
           %timeit [-n<N> -r<R> [-t|-c]] statement
         or in cell mode:
           %%timeit [-n<N> -r<R> [-t|-c]] setup_code
           code
           code...
 
         Time execution of a Python statement or expression using the timeit
         module.  This function can be used both as a line and cell magic:
 
         - In line mode you can time a single-line statement (though multiple
           ones can be chained with using semicolons).
 
         - In cell mode, the statement in the first line is used as setup code
           (executed but not timed) and the body of the cell is timed.  The cell
           body has access to any variables created in the setup code.
 
         Options:
         -n<N>: execute the given statement <N> times in a loop. If this value
         is not given, a fitting value is chosen.
 
         -r<R>: repeat the loop iteration <R> times and take the best result.
         Default: 3
 
         -t: use time.time to measure the time, which is the default on Unix.
         This function measures wall time.
 
         -c: use time.clock to measure the time, which is the default on
         Windows and measures wall time. On Unix, resource.getrusage is used
         instead and returns the CPU user time.
 
         -p<P>: use a precision of <P> digits to display the timing result.
         Default: 3
 
 
         Examples
         --------
         ::
 
           In [1]: %timeit pass
           10000000 loops, best of 3: 53.3 ns per loop
 
           In [2]: u = None
 
           In [3]: %timeit u is None
           10000000 loops, best of 3: 184 ns per loop
 
           In [4]: %timeit -r 4 u == None
           1000000 loops, best of 4: 242 ns per loop
 
           In [5]: import time
 
           In [6]: %timeit -n1 time.sleep(2)
           1 loops, best of 3: 2 s per loop
 
 
         The times reported by %timeit will be slightly higher than those
         reported by the timeit.py script when variables are accessed. This is
         due to the fact that %timeit executes the statement in the namespace
         of the shell, compared with timeit.py, which uses a single setup
         statement to import function or create variables. Generally, the bias
         does not matter as long as results from timeit.py are not mixed with
         those from %timeit."""
 
         import timeit
         import math
 
         # XXX: Unfortunately the unicode 'micro' symbol can cause problems in
         # certain terminals.  Until we figure out a robust way of
         # auto-detecting if the terminal can deal with it, use plain 'us' for
         # microseconds.  I am really NOT happy about disabling the proper
         # 'micro' prefix, but crashing is worse... If anyone knows what the
         # right solution for this is, I'm all ears...
         #
         # Note: using
         #
         # s = u'\xb5'
         # s.encode(sys.getdefaultencoding())
         #
         # is not sufficient, as I've seen terminals where that fails but
         # print s
         #
         # succeeds
         #
         # See bug: https://bugs.launchpad.net/ipython/+bug/348466
 
         #units = [u"s", u"ms",u'\xb5',"ns"]
         units = [u"s", u"ms",u'us',"ns"]
 
         scaling = [1, 1e3, 1e6, 1e9]
 
         opts, stmt = self.parse_options(line,'n:r:tcp:',
                                         posix=False, strict=False)
         if stmt == "" and cell is None:
             return
         timefunc = timeit.default_timer
         number = int(getattr(opts, "n", 0))
         repeat = int(getattr(opts, "r", timeit.default_repeat))
         precision = int(getattr(opts, "p", 3))
         if hasattr(opts, "t"):
             timefunc = time.time
         if hasattr(opts, "c"):
             timefunc = clock
 
         timer = timeit.Timer(timer=timefunc)
         # this code has tight coupling to the inner workings of timeit.Timer,
         # but is there a better way to achieve that the code stmt has access
         # to the shell namespace?
         transform  = self.shell.input_splitter.transform_cell
         if cell is None:
             # called as line magic
             setup = 'pass'
             stmt = timeit.reindent(transform(stmt), 8)
         else:
             setup = timeit.reindent(transform(stmt), 4)
             stmt = timeit.reindent(transform(cell), 8)
 
         # From Python 3.3, this template uses new-style string formatting.
         if sys.version_info >= (3, 3):
             src = timeit.template.format(stmt=stmt, setup=setup)
         else:
             src = timeit.template % dict(stmt=stmt, setup=setup)
 
         # Track compilation time so it can be reported if too long
         # Minimum time above which compilation time will be reported
         tc_min = 0.1
 
         t0 = clock()
         code = compile(src, "<magic-timeit>", "exec")
         tc = clock()-t0
 
         ns = {}
         exec code in self.shell.user_ns, ns
         timer.inner = ns["inner"]
 
         if number == 0:
             # determine number so that 0.2 <= total time < 2.0
             number = 1
             for i in range(1, 10):
                 if timer.timeit(number) >= 0.2:
                     break
                 number *= 10
 
         best = min(timer.repeat(repeat, number)) / number
 
         if best > 0.0 and best < 1000.0:
             order = min(-int(math.floor(math.log10(best)) // 3), 3)
         elif best >= 1000.0:
             order = 0
         else:
             order = 3
         print u"%d loops, best of %d: %.*g %s per loop" % (number, repeat,
                                                           precision,
                                                           best * scaling[order],
                                                           units[order])
         if tc > tc_min:
             print "Compiler time: %.2f s" % tc
 
     @skip_doctest
     @needs_local_scope
     @line_magic
     def time(self,parameter_s, user_locals):
         """Time execution of a Python statement or expression.
 
         The CPU and wall clock times are printed, and the value of the
         expression (if any) is returned.  Note that under Win32, system time
         is always reported as 0, since it can not be measured.
 
         This function provides very basic timing functionality.  In Python
         2.3, the timeit module offers more control and sophistication, so this
         could be rewritten to use it (patches welcome).
 
         Examples
         --------
         ::
 
           In [1]: time 2**128
           CPU times: user 0.00 s, sys: 0.00 s, total: 0.00 s
           Wall time: 0.00
           Out[1]: 340282366920938463463374607431768211456L
 
           In [2]: n = 1000000
 
           In [3]: time sum(range(n))
           CPU times: user 1.20 s, sys: 0.05 s, total: 1.25 s
           Wall time: 1.37
           Out[3]: 499999500000L
 
           In [4]: time print 'hello world'
           hello world
           CPU times: user 0.00 s, sys: 0.00 s, total: 0.00 s
           Wall time: 0.00
 
           Note that the time needed by Python to compile the given expression
           will be reported if it is more than 0.1s.  In this example, the
           actual exponentiation is done by Python at compilation time, so while
           the expression can take a noticeable amount of time to compute, that
           time is purely due to the compilation:
 
           In [5]: time 3**9999;
           CPU times: user 0.00 s, sys: 0.00 s, total: 0.00 s
           Wall time: 0.00 s
 
           In [6]: time 3**999999;
           CPU times: user 0.00 s, sys: 0.00 s, total: 0.00 s
           Wall time: 0.00 s
           Compiler : 0.78 s
           """
 
         # fail immediately if the given expression can't be compiled
 
         expr = self.shell.prefilter(parameter_s,False)
 
         # Minimum time above which compilation time will be reported
         tc_min = 0.1
 
         try:
             mode = 'eval'
             t0 = clock()
             code = compile(expr,'<timed eval>',mode)
             tc = clock()-t0
         except SyntaxError:
             mode = 'exec'
             t0 = clock()
             code = compile(expr,'<timed exec>',mode)
             tc = clock()-t0
         # skew measurement as little as possible
         glob = self.shell.user_ns
         wtime = time.time
         # time execution
         wall_st = wtime()
         if mode=='eval':
             st = clock2()
             out = eval(code, glob, user_locals)
             end = clock2()
         else:
             st = clock2()
             exec code in glob, user_locals
             end = clock2()
             out = None
         wall_end = wtime()
         # Compute actual times and report
         wall_time = wall_end-wall_st
         cpu_user = end[0]-st[0]
         cpu_sys = end[1]-st[1]
         cpu_tot = cpu_user+cpu_sys
         print "CPU times: user %.2f s, sys: %.2f s, total: %.2f s" % \
               (cpu_user,cpu_sys,cpu_tot)
         print "Wall time: %.2f s" % wall_time
         if tc > tc_min:
             print "Compiler : %.2f s" % tc
         return out
 
     @skip_doctest
     @line_magic
     def macro(self, parameter_s=''):
         """Define a macro for future re-execution. It accepts ranges of history,
         filenames or string objects.
 
         Usage:\\
           %macro [options] name n1-n2 n3-n4 ... n5 .. n6 ...
 
         Options:
 
           -r: use 'raw' input.  By default, the 'processed' history is used,
           so that magics are loaded in their transformed version to valid
           Python.  If this option is given, the raw input as typed as the
           command line is used instead.
 
         This will define a global variable called `name` which is a string
         made of joining the slices and lines you specify (n1,n2,... numbers
         above) from your input history into a single string. This variable
         acts like an automatic function which re-executes those lines as if
         you had typed them. You just type 'name' at the prompt and the code
         executes.
 
         The syntax for indicating input ranges is described in %history.
 
         Note: as a 'hidden' feature, you can also use traditional python slice
         notation, where N:M means numbers N through M-1.
 
         For example, if your history contains (%hist prints it)::
 
           44: x=1
           45: y=3
           46: z=x+y
           47: print x
           48: a=5
           49: print 'x',x,'y',y
 
         you can create a macro with lines 44 through 47 (included) and line 49
         called my_macro with::
 
           In [55]: %macro my_macro 44-47 49
 
         Now, typing `my_macro` (without quotes) will re-execute all this code
         in one pass.
 
         You don't need to give the line-numbers in order, and any given line
         number can appear multiple times. You can assemble macros with any
         lines from your input history in any order.
 
         The macro is a simple object which holds its value in an attribute,
         but IPython's display system checks for macros and executes them as
         code instead of printing them when you type their name.
 
         You can view a macro's contents by explicitly printing it with::
 
           print macro_name
 
         """
         opts,args = self.parse_options(parameter_s,'r',mode='list')
         if not args:   # List existing macros
             return sorted(k for k,v in self.shell.user_ns.iteritems() if\
                                                         isinstance(v, Macro))
         if len(args) == 1:
             raise UsageError(
                 "%macro insufficient args; usage '%macro name n1-n2 n3-4...")
         name, codefrom = args[0], " ".join(args[1:])
 
         #print 'rng',ranges  # dbg
         try:
             lines = self.shell.find_user_code(codefrom, 'r' in opts)
         except (ValueError, TypeError) as e:
             print e.args[0]
             return
         macro = Macro(lines)
         self.shell.define_macro(name, macro)
         print 'Macro `%s` created. To execute, type its name (without quotes).' % name
         print '=== Macro contents: ==='
         print macro,
     
     @magic_arguments.magic_arguments()
     @magic_arguments.argument('output', type=str, default='', nargs='?',
         help="""The name of the variable in which to store output.
         This is a utils.io.CapturedIO object with stdout/err attributes
         for the text of the captured output.
         
         CapturedOutput also has a show() method for displaying the output,
         and __call__ as well, so you can use that to quickly display the
         output.
         
         If unspecified, captured output is discarded.
         """
     )
     @magic_arguments.argument('--no-stderr', action="store_true",
         help="""Don't capture stderr."""
     )
     @magic_arguments.argument('--no-stdout', action="store_true",
         help="""Don't capture stdout."""
     )
     @cell_magic
     def capture(self, line, cell):
         """run the cell, capturing stdout/err"""
         args = magic_arguments.parse_argstring(self.capture, line)
         out = not args.no_stdout
         err = not args.no_stderr
         with capture_output(out, err) as io:
             self.shell.run_cell(cell)
         if args.output:
             self.shell.user_ns[args.output] = io

IPython/core/page.py

@@ -1,340 +1,340
 # encoding: utf-8
 """
 Paging capabilities for IPython.core
 
 Authors:
 
 * Brian Granger
 * Fernando Perez
 
 Notes
 -----
 
 For now this uses ipapi, so it can't be in IPython.utils.  If we can get
 rid of that dependency, we could move it there.
 -----
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2011  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import os
 import re
 import sys
 import tempfile
 
 from io import UnsupportedOperation
 
 from IPython.core import ipapi
 from IPython.core.error import TryNext
 from IPython.utils.cursesimport import use_curses
 from IPython.utils.data import chop
 from IPython.utils import io
 from IPython.utils.process import system
 from IPython.utils.terminal import get_terminal_size
 
 
 #-----------------------------------------------------------------------------
 # Classes and functions
 #-----------------------------------------------------------------------------
 
 esc_re = re.compile(r"(\x1b[^m]+m)")
 
 def page_dumb(strng, start=0, screen_lines=25):
     """Very dumb 'pager' in Python, for when nothing else works.
 
     Only moves forward, same interface as page(), except for pager_cmd and
     mode."""
 
     out_ln  = strng.splitlines()[start:]
     screens = chop(out_ln,screen_lines-1)
     if len(screens) == 1:
         print >>io.stdout, os.linesep.join(screens[0])
     else:
         last_escape = ""
         for scr in screens[0:-1]:
             hunk = os.linesep.join(scr)
             print >>io.stdout, last_escape + hunk
             if not page_more():
                 return
             esc_list = esc_re.findall(hunk)
             if len(esc_list) > 0:
                 last_escape = esc_list[-1]
         print >>io.stdout, last_escape + os.linesep.join(screens[-1])
 
 def _detect_screen_size(use_curses, screen_lines_def):
     """Attempt to work out the number of lines on the screen.
     
     This is called by page(). It can raise an error (e.g. when run in the
     test suite), so it's separated out so it can easily be called in a try block.
     """
     TERM = os.environ.get('TERM',None)
     if (TERM=='xterm' or TERM=='xterm-color') and sys.platform != 'sunos5':
         local_use_curses = use_curses
     else:
         # curses causes problems on many terminals other than xterm, and
         # some termios calls lock up on Sun OS5.
         local_use_curses = False
     if local_use_curses:
         import termios
         import curses
         # There is a bug in curses, where *sometimes* it fails to properly
         # initialize, and then after the endwin() call is made, the
         # terminal is left in an unusable state.  Rather than trying to
         # check everytime for this (by requesting and comparing termios
         # flags each time), we just save the initial terminal state and
         # unconditionally reset it every time.  It's cheaper than making
         # the checks.
         term_flags = termios.tcgetattr(sys.stdout)
 
         # Curses modifies the stdout buffer size by default, which messes
         # up Python's normal stdout buffering.  This would manifest itself
         # to IPython users as delayed printing on stdout after having used
         # the pager.
         #
         # We can prevent this by manually setting the NCURSES_NO_SETBUF
         # environment variable.  For more details, see:
         # http://bugs.python.org/issue10144
         NCURSES_NO_SETBUF = os.environ.get('NCURSES_NO_SETBUF', None)
         os.environ['NCURSES_NO_SETBUF'] = ''
         
         # Proceed with curses initialization
         scr = curses.initscr()
         screen_lines_real,screen_cols = scr.getmaxyx()
         curses.endwin()
 
         # Restore environment
         if NCURSES_NO_SETBUF is None:
             del os.environ['NCURSES_NO_SETBUF']
         else:
             os.environ['NCURSES_NO_SETBUF'] = NCURSES_NO_SETBUF
             
         # Restore terminal state in case endwin() didn't.
         termios.tcsetattr(sys.stdout,termios.TCSANOW,term_flags)
         # Now we have what we needed: the screen size in rows/columns
         return screen_lines_real
         #print '***Screen size:',screen_lines_real,'lines x',\
         #screen_cols,'columns.' # dbg
     else:
         return screen_lines_def
 
 def page(strng, start=0, screen_lines=0, pager_cmd=None):
     """Print a string, piping through a pager after a certain length.
 
     The screen_lines parameter specifies the number of *usable* lines of your
     terminal screen (total lines minus lines you need to reserve to show other
     information).
 
     If you set screen_lines to a number <=0, page() will try to auto-determine
     your screen size and will only use up to (screen_size+screen_lines) for
     printing, paging after that. That is, if you want auto-detection but need
     to reserve the bottom 3 lines of the screen, use screen_lines = -3, and for
     auto-detection without any lines reserved simply use screen_lines = 0.
 
     If a string won't fit in the allowed lines, it is sent through the
     specified pager command. If none given, look for PAGER in the environment,
     and ultimately default to less.
 
     If no system pager works, the string is sent through a 'dumb pager'
     written in python, very simplistic.
     """
 
     # Some routines may auto-compute start offsets incorrectly and pass a
     # negative value.  Offset to 0 for robustness.
     start = max(0, start)
 
     # first, try the hook
     ip = ipapi.get()
     if ip:
         try:
             ip.hooks.show_in_pager(strng)
             return
         except TryNext:
             pass
 
     # Ugly kludge, but calling curses.initscr() flat out crashes in emacs
     TERM = os.environ.get('TERM','dumb')
     if TERM in ['dumb','emacs'] and os.name != 'nt':
         print strng
         return
     # chop off the topmost part of the string we don't want to see
     str_lines = strng.splitlines()[start:]
     str_toprint = os.linesep.join(str_lines)
     num_newlines = len(str_lines)
     len_str = len(str_toprint)
 
     # Dumb heuristics to guesstimate number of on-screen lines the string
     # takes.  Very basic, but good enough for docstrings in reasonable
     # terminals. If someone later feels like refining it, it's not hard.
     numlines = max(num_newlines,int(len_str/80)+1)
 
     screen_lines_def = get_terminal_size()[1]
 
     # auto-determine screen size
     if screen_lines <= 0:
         try:
             screen_lines += _detect_screen_size(use_curses, screen_lines_def)
         except (TypeError, UnsupportedOperation):
             print >>io.stdout, str_toprint
             return
 
     #print 'numlines',numlines,'screenlines',screen_lines  # dbg
     if numlines <= screen_lines :
         #print '*** normal print'  # dbg
         print >>io.stdout, str_toprint
     else:
         # Try to open pager and default to internal one if that fails.
         # All failure modes are tagged as 'retval=1', to match the return
         # value of a failed system command.  If any intermediate attempt
         # sets retval to 1, at the end we resort to our own page_dumb() pager.
         pager_cmd = get_pager_cmd(pager_cmd)
         pager_cmd += ' ' + get_pager_start(pager_cmd,start)
         if os.name == 'nt':
             if pager_cmd.startswith('type'):
                 # The default WinXP 'type' command is failing on complex strings.
                 retval = 1
             else:
                 tmpname = tempfile.mktemp('.txt')
                 tmpfile = open(tmpname,'wt')
                 tmpfile.write(strng)
                 tmpfile.close()
                 cmd = "%s < %s" % (pager_cmd,tmpname)
                 if os.system(cmd):
                   retval = 1
                 else:
                   retval = None
                 os.remove(tmpname)
         else:
             try:
                 retval = None
                 # if I use popen4, things hang. No idea why.
                 #pager,shell_out = os.popen4(pager_cmd)
                 pager = os.popen(pager_cmd,'w')
                 pager.write(strng)
                 pager.close()
                 retval = pager.close()  # success returns None
             except IOError as msg:  # broken pipe when user quits
                 if msg.args == (32,'Broken pipe'):
                     retval = None
                 else:
                     retval = 1
             except OSError:
                 # Other strange problems, sometimes seen in Win2k/cygwin
                 retval = 1
         if retval is not None:
             page_dumb(strng,screen_lines=screen_lines)
 
 
 def page_file(fname, start=0, pager_cmd=None):
     """Page a file, using an optional pager command and starting line.
     """
 
     pager_cmd = get_pager_cmd(pager_cmd)
     pager_cmd += ' ' + get_pager_start(pager_cmd,start)
 
     try:
         if os.environ['TERM'] in ['emacs','dumb']:
             raise EnvironmentError
         system(pager_cmd + ' ' + fname)
     except:
         try:
             if start > 0:
                 start -= 1
             page(open(fname).read(),start)
         except:
-            print 'Unable to show file',`fname`
+            print 'Unable to show file',repr(fname)
 
 
 def get_pager_cmd(pager_cmd=None):
     """Return a pager command.
 
     Makes some attempts at finding an OS-correct one.
     """
     if os.name == 'posix':
         default_pager_cmd = 'less -r'  # -r for color control sequences
     elif os.name in ['nt','dos']:
         default_pager_cmd = 'type'
 
     if pager_cmd is None:
         try:
             pager_cmd = os.environ['PAGER']
         except:
             pager_cmd = default_pager_cmd
     return pager_cmd
 
 
 def get_pager_start(pager, start):
     """Return the string for paging files with an offset.
 
     This is the '+N' argument which less and more (under Unix) accept.
     """
 
     if pager in ['less','more']:
         if start:
             start_string = '+' + str(start)
         else:
             start_string = ''
     else:
         start_string = ''
     return start_string
 
 
 # (X)emacs on win32 doesn't like to be bypassed with msvcrt.getch()
 if os.name == 'nt' and os.environ.get('TERM','dumb') != 'emacs':
     import msvcrt
     def page_more():
         """ Smart pausing between pages
 
         @return:    True if need print more lines, False if quit
         """
         io.stdout.write('---Return to continue, q to quit--- ')
         ans = msvcrt.getch()
         if ans in ("q", "Q"):
             result = False
         else:
             result = True
         io.stdout.write("\b"*37 + " "*37 + "\b"*37)
         return result
 else:
     def page_more():
         ans = raw_input('---Return to continue, q to quit--- ')
         if ans.lower().startswith('q'):
             return False
         else:
             return True
 
 
 def snip_print(str,width = 75,print_full = 0,header = ''):
     """Print a string snipping the midsection to fit in width.
 
     print_full: mode control:
       - 0: only snip long strings
       - 1: send to page() directly.
       - 2: snip long strings and ask for full length viewing with page()
     Return 1 if snipping was necessary, 0 otherwise."""
 
     if print_full == 1:
         page(header+str)
         return 0
 
     print header,
     if len(str) < width:
         print str
         snip = 0
     else:
         whalf = int((width -5)/2)
         print str[:whalf] + ' <...> ' + str[-whalf:]
         snip = 1
     if snip and print_full == 2:
         if raw_input(header+' Snipped. View (y/n)? [N]').lower() == 'y':
             page(str)
     return snip