Fix small inconsistency in display hook (needed for a SAGE fix)

IPython/Prompts.py

@@ -1,586 +1,585 b''
 # -*- coding: utf-8 -*-
 """
 Classes for handling input/output prompts.
 
-$Id: Prompts.py 1272 2006-04-25 17:04:17Z vivainio $"""
+$Id: Prompts.py 1303 2006-05-17 03:39:29Z fperez $"""
 
 #*****************************************************************************
 #       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.
 #*****************************************************************************
 
 from IPython import Release
 __author__  = '%s <%s>' % Release.authors['Fernando']
 __license__ = Release.license
 __version__ = Release.version
 
 #****************************************************************************
 # Required modules
 import __builtin__
 import os
 import socket
 import sys
 import time
-from pprint import pprint,pformat
 
 # IPython's own
 from IPython import ColorANSI
 from IPython.Itpl import ItplNS
 from IPython.ipstruct import Struct
 from IPython.macro import Macro
 from IPython.genutils import *
 
 #****************************************************************************
 #Color schemes for Prompts.
 
 PromptColors = ColorANSI.ColorSchemeTable()
 InputColors = ColorANSI.InputTermColors  # just a shorthand
 Colors = ColorANSI.TermColors  # just a shorthand
 
 PromptColors.add_scheme(ColorANSI.ColorScheme(
     'NoColor',
     in_prompt  = InputColors.NoColor,  # Input prompt
     in_number  = InputColors.NoColor,  # Input prompt number
     in_prompt2 = InputColors.NoColor, # Continuation prompt
     in_normal  = InputColors.NoColor,  # color off (usu. Colors.Normal)
     
     out_prompt = Colors.NoColor, # Output prompt
     out_number = Colors.NoColor, # Output prompt number
 
     normal = Colors.NoColor  # color off (usu. Colors.Normal)
     ))
 
 # make some schemes as instances so we can copy them for modification easily:
 __PColLinux =  ColorANSI.ColorScheme(
     'Linux',
     in_prompt  = InputColors.Green,
     in_number  = InputColors.LightGreen,
     in_prompt2 = InputColors.Green,
     in_normal  = InputColors.Normal,  # color off (usu. Colors.Normal)
 
     out_prompt = Colors.Red,
     out_number = Colors.LightRed,
 
     normal = Colors.Normal
     )
 # Don't forget to enter it into the table!
 PromptColors.add_scheme(__PColLinux)
 
 # Slightly modified Linux for light backgrounds
 __PColLightBG  = __PColLinux.copy('LightBG')
 
 __PColLightBG.colors.update(
     in_prompt  = InputColors.Blue,
     in_number  = InputColors.LightBlue,
     in_prompt2 = InputColors.Blue
 )
 PromptColors.add_scheme(__PColLightBG)
 
 del Colors,InputColors
 
 #-----------------------------------------------------------------------------
 def multiple_replace(dict, text):
     """ Replace in 'text' all occurences of any key in the given
     dictionary by its corresponding value.  Returns the new string."""
 
     # Function by Xavier Defrang, originally found at:
     # http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/81330
 
     # Create a regular expression  from the dictionary keys
     regex = re.compile("(%s)" % "|".join(map(re.escape, dict.keys())))
     # For each match, look-up corresponding value in dictionary
     return regex.sub(lambda mo: dict[mo.string[mo.start():mo.end()]], text)
 
 #-----------------------------------------------------------------------------
 # Special characters that can be used in prompt templates, mainly bash-like
 
 # If $HOME isn't defined (Windows), make it an absurd string so that it can
 # never be expanded out into '~'.  Basically anything which can never be a
 # reasonable directory name will do, we just want the $HOME -> '~' operation
 # to become a no-op.  We pre-compute $HOME here so it's not done on every
 # prompt call.
 
 # FIXME:
 
 # - This should be turned into a class which does proper namespace management,
 # since the prompt specials need to be evaluated in a certain namespace.
 # Currently it's just globals, which need to be managed manually by code
 # below.
 
 # - I also need to split up the color schemes from the prompt specials
 # somehow.  I don't have a clean design for that quite yet.
 
 HOME = os.environ.get("HOME","//////:::::ZZZZZ,,,~~~")
 
 # We precompute a few more strings here for the prompt_specials, which are
 # fixed once ipython starts.  This reduces the runtime overhead of computing
 # prompt strings.
 USER           = os.environ.get("USER")
 HOSTNAME       = socket.gethostname()
 HOSTNAME_SHORT = HOSTNAME.split(".")[0]
 ROOT_SYMBOL    = "$#"[os.name=='nt' or os.getuid()==0]
 
 prompt_specials_color = {
     # Prompt/history count
     '%n' : '${self.col_num}' '${self.cache.prompt_count}' '${self.col_p}',
     '\\#': '${self.col_num}' '${self.cache.prompt_count}' '${self.col_p}',
     # Prompt/history count, with the actual digits replaced by dots.  Used
     # mainly in continuation prompts (prompt_in2)
     '\\D': '${"."*len(str(self.cache.prompt_count))}',
     # Current working directory
     '\\w': '${os.getcwd()}',
     # Current time
     '\\t' : '${time.strftime("%H:%M:%S")}',
     # Basename of current working directory.
     # (use os.sep to make this portable across OSes)
     '\\W' : '${os.getcwd().split("%s")[-1]}' % os.sep,
     # These X<N> are an extension to the normal bash prompts.  They return
     # N terms of the path, after replacing $HOME with '~'
     '\\X0': '${os.getcwd().replace("%s","~")}' % HOME,
     '\\X1': '${self.cwd_filt(1)}',
     '\\X2': '${self.cwd_filt(2)}',
     '\\X3': '${self.cwd_filt(3)}',
     '\\X4': '${self.cwd_filt(4)}',
     '\\X5': '${self.cwd_filt(5)}',
     # Y<N> are similar to X<N>, but they show '~' if it's the directory
     # N+1 in the list.  Somewhat like %cN in tcsh.
     '\\Y0': '${self.cwd_filt2(0)}',
     '\\Y1': '${self.cwd_filt2(1)}',
     '\\Y2': '${self.cwd_filt2(2)}',
     '\\Y3': '${self.cwd_filt2(3)}',
     '\\Y4': '${self.cwd_filt2(4)}',
     '\\Y5': '${self.cwd_filt2(5)}',
     # Hostname up to first .
     '\\h': HOSTNAME_SHORT,
     # Full hostname
     '\\H': HOSTNAME,
     # Username of current user
     '\\u': USER,
     # Escaped '\'
     '\\\\': '\\',
     # Newline
     '\\n': '\n',
     # Carriage return
     '\\r': '\r',
     # Release version
     '\\v': __version__,
     # Root symbol ($ or #)
     '\\$': ROOT_SYMBOL,
     }
 
 # A copy of the prompt_specials dictionary but with all color escapes removed,
 # so we can correctly compute the prompt length for the auto_rewrite method.
 prompt_specials_nocolor = prompt_specials_color.copy()
 prompt_specials_nocolor['%n'] = '${self.cache.prompt_count}'
 prompt_specials_nocolor['\\#'] = '${self.cache.prompt_count}'
 
 # Add in all the InputTermColors color escapes as valid prompt characters.
 # They all get added as \\C_COLORNAME, so that we don't have any conflicts
 # with a color name which may begin with a letter used by any other of the
 # allowed specials.  This of course means that \\C will never be allowed for
 # anything else.
 input_colors = ColorANSI.InputTermColors
 for _color in dir(input_colors):
     if _color[0] != '_':
         c_name = '\\C_'+_color
         prompt_specials_color[c_name] = getattr(input_colors,_color)
         prompt_specials_nocolor[c_name] = ''
 
 # we default to no color for safety.  Note that prompt_specials is a global
 # variable used by all prompt objects.
 prompt_specials = prompt_specials_nocolor
 
 #-----------------------------------------------------------------------------
 def str_safe(arg):
     """Convert to a string, without ever raising an exception.
 
     If str(arg) fails, <ERROR: ... > is returned, where ... is the exception
     error message."""
 
     try:
         out = str(arg)
     except UnicodeError:
         try:
             out = arg.encode('utf_8','replace')
         except Exception,msg:
             # let's keep this little duplication here, so that the most common
             # case doesn't suffer from a double try wrapping.
             out = '<ERROR: %s>' % msg
     except Exception,msg:
         out = '<ERROR: %s>' % msg
     return out
 
 class BasePrompt:
     """Interactive prompt similar to Mathematica's."""
     def __init__(self,cache,sep,prompt,pad_left=False):
 
         # Hack: we access information about the primary prompt through the
         # cache argument.  We need this, because we want the secondary prompt
         # to be aligned with the primary one.  Color table info is also shared
         # by all prompt classes through the cache.  Nice OO spaghetti code!
         self.cache = cache
         self.sep = sep
         
         # regexp to count the number of spaces at the end of a prompt
         # expression, useful for prompt auto-rewriting
         self.rspace = re.compile(r'(\s*)$')
         # Flag to left-pad prompt strings to match the length of the primary
         # prompt
         self.pad_left = pad_left
         # Set template to create each actual prompt (where numbers change)
         self.p_template = prompt
         self.set_p_str()
 
     def set_p_str(self):
         """ Set the interpolating prompt strings.
 
         This must be called every time the color settings change, because the
         prompt_specials global may have changed."""
 
         import os,time  # needed in locals for prompt string handling
         loc = locals()
         self.p_str = ItplNS('%s%s%s' %
                             ('${self.sep}${self.col_p}',
                              multiple_replace(prompt_specials, self.p_template),
                              '${self.col_norm}'),self.cache.user_ns,loc)
         
         self.p_str_nocolor = ItplNS(multiple_replace(prompt_specials_nocolor,
                                                      self.p_template),
                                     self.cache.user_ns,loc)
 
     def write(self,msg):  # dbg
         sys.stdout.write(msg)
         return ''
 
     def __str__(self):
         """Return a string form of the prompt.
 
         This for is useful for continuation and output prompts, since it is
         left-padded to match lengths with the primary one (if the
         self.pad_left attribute is set)."""
 
         out_str = str_safe(self.p_str)
         if self.pad_left:
             # We must find the amount of padding required to match lengths,
             # taking the color escapes (which are invisible on-screen) into
             # account.
             esc_pad = len(out_str) - len(str_safe(self.p_str_nocolor))
             format = '%%%ss' % (len(str(self.cache.last_prompt))+esc_pad)
             return format % out_str
         else:
             return out_str
 
     # these path filters are put in as methods so that we can control the
     # namespace where the prompt strings get evaluated
     def cwd_filt(self,depth):
         """Return the last depth elements of the current working directory.
 
         $HOME is always replaced with '~'.
         If depth==0, the full path is returned."""
 
         cwd = os.getcwd().replace(HOME,"~")
         out = os.sep.join(cwd.split(os.sep)[-depth:])
         if out:
             return out
         else:
             return os.sep
 
     def cwd_filt2(self,depth):
         """Return the last depth elements of the current working directory.
 
         $HOME is always replaced with '~'.
         If depth==0, the full path is returned."""
 
         cwd = os.getcwd().replace(HOME,"~").split(os.sep)
         if '~' in cwd and len(cwd) == depth+1:
             depth += 1
         out = os.sep.join(cwd[-depth:])
         if out:
             return out
         else:
             return os.sep
 
 class Prompt1(BasePrompt):
     """Input interactive prompt similar to Mathematica's."""
 
     def __init__(self,cache,sep='\n',prompt='In [\\#]: ',pad_left=True):
         BasePrompt.__init__(self,cache,sep,prompt,pad_left)
 
     def set_colors(self):
         self.set_p_str()
         Colors = self.cache.color_table.active_colors # shorthand
         self.col_p = Colors.in_prompt
         self.col_num = Colors.in_number
         self.col_norm = Colors.in_normal
         # We need a non-input version of these escapes for the '--->'
         # auto-call prompts used in the auto_rewrite() method.
         self.col_p_ni = self.col_p.replace('\001','').replace('\002','') 
         self.col_norm_ni = Colors.normal        
         
     def __str__(self):
         self.cache.prompt_count += 1
         self.cache.last_prompt = str_safe(self.p_str_nocolor).split('\n')[-1]
         return str_safe(self.p_str)
 
     def auto_rewrite(self):
         """Print a string of the form '--->' which lines up with the previous
         input string. Useful for systems which re-write the user input when
         handling automatically special syntaxes."""
 
         curr = str(self.cache.last_prompt)
         nrspaces = len(self.rspace.search(curr).group())
         return '%s%s>%s%s' % (self.col_p_ni,'-'*(len(curr)-nrspaces-1),
                               ' '*nrspaces,self.col_norm_ni)
 
 class PromptOut(BasePrompt):
     """Output interactive prompt similar to Mathematica's."""
 
     def __init__(self,cache,sep='',prompt='Out[\\#]: ',pad_left=True):
         BasePrompt.__init__(self,cache,sep,prompt,pad_left)
         if not self.p_template:
             self.__str__ = lambda: ''
 
     def set_colors(self):
         self.set_p_str()
         Colors = self.cache.color_table.active_colors # shorthand
         self.col_p = Colors.out_prompt
         self.col_num = Colors.out_number
         self.col_norm = Colors.normal
 
 class Prompt2(BasePrompt):
     """Interactive continuation prompt."""
     
     def __init__(self,cache,prompt='   .\\D.: ',pad_left=True):
         self.cache = cache
         self.p_template = prompt
         self.pad_left = pad_left
         self.set_p_str()
 
     def set_p_str(self):
         import os,time  # needed in locals for prompt string handling
         loc = locals()
         self.p_str = ItplNS('%s%s%s' %
                             ('${self.col_p2}',
                              multiple_replace(prompt_specials, self.p_template),
                              '$self.col_norm'),
                             self.cache.user_ns,loc)
         self.p_str_nocolor = ItplNS(multiple_replace(prompt_specials_nocolor,
                                                      self.p_template),
                                     self.cache.user_ns,loc)
 
     def set_colors(self):
         self.set_p_str()
         Colors = self.cache.color_table.active_colors
         self.col_p2 = Colors.in_prompt2
         self.col_norm = Colors.in_normal
         # FIXME (2004-06-16) HACK: prevent crashes for users who haven't
         # updated their prompt_in2 definitions.  Remove eventually.
         self.col_p = Colors.out_prompt
         self.col_num = Colors.out_number
 
 #-----------------------------------------------------------------------------
 class CachedOutput:
     """Class for printing output from calculations while keeping a cache of
     reults. It dynamically creates global variables prefixed with _ which
     contain these results.
 
     Meant to be used as a sys.displayhook replacement, providing numbered
     prompts and cache services.
 
     Initialize with initial and final values for cache counter (this defines
     the maximum size of the cache."""
 
     def __init__(self,shell,cache_size,Pprint,
                  colors='NoColor',input_sep='\n',
                  output_sep='\n',output_sep2='',
                  ps1 = None, ps2 = None,ps_out = None,pad_left=True):
 
         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
         self.input_sep = input_sep
 
         # we need a reference to the user-level namespace
         self.shell = shell
         self.user_ns = shell.user_ns
         # and to the user's input
         self.input_hist = shell.input_hist
         # and to the user's logger, for logging output
         self.logger = shell.logger
 
         # Set input prompt strings and colors
         if cache_size == 0:
             if ps1.find('%n') > -1 or ps1.find('\\#') > -1: ps1 = '>>> '
             if ps2.find('%n') > -1 or ps2.find('\\#') > -1: ps2 = '... '
         self.ps1_str = self._set_prompt_str(ps1,'In [\\#]: ','>>> ')
         self.ps2_str = self._set_prompt_str(ps2,'   .\\D.: ','... ')
         self.ps_out_str = self._set_prompt_str(ps_out,'Out[\\#]: ','')
 
         self.color_table = PromptColors
         self.prompt1 = Prompt1(self,sep=input_sep,prompt=self.ps1_str,
                                pad_left=pad_left)
         self.prompt2 = Prompt2(self,prompt=self.ps2_str,pad_left=pad_left)
         self.prompt_out = PromptOut(self,sep='',prompt=self.ps_out_str,
                                     pad_left=pad_left)
         self.set_colors(colors)
 
         # other more normal stuff
         # b/c each call to the In[] prompt raises it by 1, even the first.
         self.prompt_count = 0
         # Store the last prompt string each time, we need it for aligning
         # continuation and auto-rewrite prompts
         self.last_prompt = ''
         self.Pprint = Pprint
         self.output_sep = output_sep
         self.output_sep2 = output_sep2
         self._,self.__,self.___ = '','',''
         self.pprint_types = map(type,[(),[],{}])
         
         # these are deliberately global:
         to_user_ns = {'_':self._,'__':self.__,'___':self.___}
         self.user_ns.update(to_user_ns)
 
     def _set_prompt_str(self,p_str,cache_def,no_cache_def):
         if p_str is None:
             if self.do_full_cache:
                 return cache_def
             else:
                 return no_cache_def
         else:
             return p_str
                 
     def set_colors(self,colors):
         """Set the active color scheme and configure colors for the three
         prompt subsystems."""
 
         # FIXME: the prompt_specials global should be gobbled inside this
         # class instead.  Do it when cleaning up the whole 3-prompt system.
         global prompt_specials
         if colors.lower()=='nocolor':
             prompt_specials = prompt_specials_nocolor
         else:
             prompt_specials = prompt_specials_color
         
         self.color_table.set_active_scheme(colors)
         self.prompt1.set_colors()
         self.prompt2.set_colors()
         self.prompt_out.set_colors()
 
     def __call__(self,arg=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."""
 
         # 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.user_ns['_']
             except KeyError:
                 pass
         if arg is not None:
             cout_write = Term.cout.write # fast lookup
             # first handle the cache and counters
 
             # do not print output if input ends in ';'
             if self.input_hist[self.prompt_count].endswith(';\n'):
                 return
             # don't use print, puts an extra space
             cout_write(self.output_sep)
             if self.do_full_cache:
                 cout_write(str(self.prompt_out))
 
             if isinstance(arg,Macro):
                 print 'Executing Macro...'
                 # in case the macro takes a long time to execute
                 Term.cout.flush()
                 self.shell.runlines(arg.value)
                 return None
 
             # and now call a possibly user-defined print mechanism
             manipulated_val = self.display(arg)
             
             # user display hooks can change the variable to be stored in
             # output history
             
             if manipulated_val is not None:
                 arg = manipulated_val
                 
             # avoid recursive reference when displaying _oh/Out
             if arg is not self.user_ns['_oh']:
                 self.update(arg)
 
             if self.logger.log_output:
                 self.logger.log_write(repr(arg),'output')
             cout_write(self.output_sep2)
             Term.cout.flush()
 
     def _display(self,arg):
         """Default printer method, uses pprint.
 
         Do ip.set_hook("result_display", my_displayhook) for custom result
         display, e.g. when your own objects need special formatting.
         """
 
         return self.shell.hooks.result_display(arg)
 
     # Assign the default display method:
     display = _display
 
     def update(self,arg):
         #print '***cache_count', self.cache_count # dbg
         if len(self.user_ns['_oh']) >= self.cache_size and self.do_full_cache:
             warn('Output cache limit (currently '+
                   `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._ = arg
             self.user_ns.update({'_':self._,'__':self.__,'___':self.___})
             
         # hackish access to top-level  namespace to create _1,_2... dynamically
         to_main = {}
         if self.do_full_cache:
             new_result = '_'+`self.prompt_count`
             to_main[new_result] = arg
         self.user_ns.update(to_main)
         self.user_ns['_oh'][self.prompt_count] = arg
 
     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`
             try:
                 del self.user_ns[key]
             except: pass
         self.user_ns['_oh'].clear()
         
         if '_' not in __builtin__.__dict__:
             self.user_ns.update({'_':None,'__':None, '___':None})
         import gc
         gc.collect() # xxx needed?

IPython/hooks.py

@@ -1,191 +1,196 b''
 """hooks for IPython.
 
 In Python, it is possible to overwrite any method of any object if you really
 want to.  But IPython exposes a few 'hooks', methods which are _designed_ to
 be overwritten by users for customization purposes.  This module defines the
 default versions of all such hooks, which get used by IPython if not
 overridden by the user.
 
 hooks are simple functions, but they should be declared with 'self' as their
 first argument, because when activated they are registered into IPython as
 instance methods.  The self argument will be the IPython running instance
 itself, so hooks have full access to the entire IPython object.
 
 If you wish to define a new hook and activate it, you need to put the
 necessary code into a python file which can be either imported or execfile()'d
 from within your ipythonrc configuration.
 
 For example, suppose that you have a module called 'myiphooks' in your
 PYTHONPATH, which contains the following definition:
 
 import os
 import IPython.ipapi
 ip = IPython.ipapi.get()
 
 def calljed(self,filename, linenum):
     "My editor hook calls the jed editor directly."
     print "Calling my own editor, jed ..."
     os.system('jed +%d %s' % (linenum,filename))
 
 ip.set_hook('editor', calljed)
 
 You can then enable the functionality by doing 'import myiphooks'
 somewhere in your configuration files or ipython command line.
 
-$Id: hooks.py 1274 2006-04-26 14:01:37Z vivainio $"""
+$Id: hooks.py 1303 2006-05-17 03:39:29Z fperez $"""
 
 #*****************************************************************************
 #       Copyright (C) 2005 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.
 #*****************************************************************************
 
 from IPython import Release
 from IPython import ipapi
 __author__  = '%s <%s>' % Release.authors['Fernando']
 __license__ = Release.license
 __version__ = Release.version
 
 import os,bisect
 from genutils import Term
-from pprint import pformat
+from pprint import PrettyPrinter
 
 # List here all the default hooks.  For now it's just the editor functions
 # but over time we'll move here all the public API for user-accessible things.
 __all__ = ['editor', 'fix_error_editor', 'result_display',
            'input_prefilter', 'shutdown_hook', 'late_startup_hook']
 
+pformat = PrettyPrinter().pformat
+
 def editor(self,filename, linenum=None):
     """Open the default editor at the given filename and linenumber.
 
     This is IPython's default editor hook, you can use it as an example to
     write your own modified one.  To set your own editor function as the
     new editor hook, call ip.set_hook('editor',yourfunc)."""
 
     # IPython configures a default editor at startup by reading $EDITOR from
     # the environment, and falling back on vi (unix) or notepad (win32).
     editor = self.rc.editor
     
     # marker for at which line to open the file (for existing objects)
     if linenum is None or editor=='notepad':
         linemark = ''
     else:
         linemark = '+%d' % linenum
     
     # Enclose in quotes if necessary and legal
     if ' ' in editor and os.path.isfile(editor) and editor[0] != '"':
         editor = '"%s"' % editor
         
     # Call the actual editor
     os.system('%s %s %s' % (editor,linemark,filename))
 
 import tempfile
 def fix_error_editor(self,filename,linenum,column,msg):
     """Open the editor at the given filename, linenumber, column and 
     show an error message. This is used for correcting syntax errors.
     The current implementation only has special support for the VIM editor,
     and falls back on the 'editor' hook if VIM is not used.
 
     Call ip.set_hook('fix_error_editor',youfunc) to use your own function,
     """
     def vim_quickfix_file():
         t = tempfile.NamedTemporaryFile()
         t.write('%s:%d:%d:%s\n' % (filename,linenum,column,msg))
         t.flush()
         return t
     if os.path.basename(self.rc.editor) != 'vim':
         self.hooks.editor(filename,linenum)
         return
     t = vim_quickfix_file()
     try:
         os.system('vim --cmd "set errorformat=%f:%l:%c:%m" -q ' + t.name)
     finally:
         t.close()
 
 
 class CommandChainDispatcher:
     """ Dispatch calls to a chain of commands until some func can handle it
     
     Usage: instantiate, execute "add" to add commands (with optional
     priority), execute normally via f() calling mechanism.
     
     """
     def __init__(self,commands=None):
         if commands is None:
             self.chain = []
         else:
             self.chain = commands
             
             
     def __call__(self,*args, **kw):
         """ Command chain is called just like normal func. 
         
         This will call all funcs in chain with the same args as were given to this
         function, and return the result of first func that didn't raise
         TryNext """
         
         for prio,cmd in self.chain:
             #print "prio",prio,"cmd",cmd #dbg
             try:
                 ret = cmd(*args, **kw)
                 return ret
             except ipapi.TryNext, exc:
                 if exc.args or exc.kwargs:
                     args = exc.args
                     kw = exc.kwargs
                 
     def __str__(self):
         return str(self.chain)
     
     def add(self, func, priority=0):
         """ Add a func to the cmd chain with given priority """
         bisect.insort(self.chain,(priority,func))
 
 def result_display(self,arg):
     """ Default display hook.
     
     Called for displaying the result to the user.
     """
     
     if self.rc.pprint:
         out = pformat(arg)
         if '\n' in out:
             # 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.                
             Term.cout.write('\n')
         print >>Term.cout, out
     else:
-        print >>Term.cout, arg
-    # the default display hook doesn't manipulate the value to put in history    
+        # By default, the interactive prompt uses repr() to display results,
+        # so we should honor this.  Users who'd rather use a different
+        # mechanism can easily override this hook.
+        print >>Term.cout, repr(arg)
+    # the default display hook doesn't manipulate the value to put in history
     return None 
 
 def input_prefilter(self,line):     
     """ Default input prefilter
     
     This returns the line as unchanged, so that the interpreter
     knows that nothing was done and proceeds with "classic" prefiltering
     (%magics, !shell commands etc.). 
     
     Note that leading whitespace is not passed to this hook. Prefilter
     can't alter indentation.
     
     """
     #print "attempt to rewrite",line #dbg
     return line
 
 def shutdown_hook(self):
     """ default shutdown hook
     
     Typically, shotdown hooks should raise TryNext so all shutdown ops are done
     """
     
     #print "default shutdown hook ok" # dbg
     return
 
 def late_startup_hook(self):
     """ Executed after ipython has been constructed and configured 
     
     """
     #print "default startup hook ok" # dbg