Work around bug in pprint.pformat. Closes gh-148

IPython/core/displayhook.py

@@ -1,288 +1,292 b''
 # -*- coding: utf-8 -*-
 """Displayhook for IPython.
 
 Authors:
 
 * Fernando Perez
 * Brian Granger
 """
 
 #-----------------------------------------------------------------------------
 #       Copyright (C) 2008-2010 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 pprint import PrettyPrinter
 pformat = PrettyPrinter().pformat
 
 from IPython.config.configurable import Configurable
 from IPython.core import prompts
 import IPython.utils.generics
 import IPython.utils.io
 from IPython.utils.traitlets import Instance, Int
 from IPython.utils.warn import warn
 
 #-----------------------------------------------------------------------------
 # Main displayhook class
 #-----------------------------------------------------------------------------
 
 # TODO: The DisplayHook class should be split into two classes, one that
 # manages the prompts and their synchronization and another that just does the
 # displayhook logic and calls into the prompt manager.
 
 # TODO: Move the various attributes (cache_size, colors, input_sep,
 # output_sep, output_sep2, ps1, ps2, ps_out, pad_left). 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.
 
     Currently this class does more than just the displayhook logic and that
     extra logic should eventually be moved out of here.
     """
 
     shell = Instance('IPython.core.interactiveshell.InteractiveShellABC')
     # Each call to the In[] prompt raises it by 1, even the first.
     prompt_count = Int(0)
 
     def __init__(self, shell=None, cache_size=1000,
                  colors='NoColor', input_sep='\n',
                  output_sep='\n', output_sep2='',
                  ps1 = None, ps2 = None, ps_out = None, pad_left=True,
                  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
         self.input_sep = input_sep
 
         # we need a reference to the user-level namespace
         self.shell = shell
 
         # Set input prompt strings and colors
         if cache_size == 0:
             if ps1.find('%n') > -1 or ps1.find(r'\#') > -1 \
                    or ps1.find(r'\N') > -1:
                 ps1 = '>>> '
             if ps2.find('%n') > -1 or ps2.find(r'\#') > -1 \
                    or ps2.find(r'\N') > -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 = prompts.PromptColors
         self.prompt1 = prompts.Prompt1(self,sep=input_sep,prompt=self.ps1_str,
                                pad_left=pad_left)
         self.prompt2 = prompts.Prompt2(self,prompt=self.ps2_str,pad_left=pad_left)
         self.prompt_out = prompts.PromptOut(self,sep='',prompt=self.ps_out_str,
                                     pad_left=pad_left)
         self.set_colors(colors)
 
         # Store the last prompt string each time, we need it for aligning
         # continuation and auto-rewrite prompts
         self.last_prompt = ''
         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.shell.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: This modifying of the global prompts.prompt_specials needs
         # to be fixed. We need to refactor all of the prompts stuff to use
         # proper configuration and traits notifications.
         if colors.lower()=='nocolor':
             prompts.prompt_specials = prompts.prompt_specials_nocolor
         else:
             prompts.prompt_specials = prompts.prompt_specials_color
         
         self.color_table.set_active_scheme(colors)
         self.prompt1.set_colors()
         self.prompt2.set_colors()
         self.prompt_out.set_colors()
 
     #-------------------------------------------------------------------------
     # 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:
             if self.shell.input_hist[self.prompt_count].endswith(';\n'):
                 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."""
         # Use write, not print which adds an extra space.
         IPython.utils.io.Term.cout.write(self.output_sep)
         outprompt = str(self.prompt_out)
         if self.do_full_cache:
             IPython.utils.io.Term.cout.write(outprompt)
 
     # TODO: Make this method an extension point. The previous implementation
     # has both a result_display hook as well as a result_display generic
     # function to customize the repr on a per class basis. We need to rethink
     # the hooks mechanism before doing this though.
     def compute_result_repr(self, result):
         """Compute and return the repr of the object to be displayed.
 
         This method only compute the string form of the repr and should NOT
         actual print or write that to a stream. This method may also transform
         the result itself, but the default implementation passes the original
         through.
         """
         try:
             if self.shell.pprint:
+                try:
                 result_repr = pformat(result)
+                except:
+                    # Work around possible bugs in pformat
+                    result_repr = repr(result)
                 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.
                     result_repr = '\n' + result_repr
             else:
                 result_repr = repr(result)
         except TypeError:
             # This happens when result.__repr__ doesn't return a string,
             # such as when it returns None.
             result_repr = '\n'
         return result, result_repr
 
     def write_result_repr(self, result_repr):
         # 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.
         print >>IPython.utils.io.Term.cout, 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'
                      '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.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] = result
                 self.shell.user_ns.update(to_main)
                 self.shell.user_ns['_oh'][self.prompt_count] = result
 
     def log_output(self, result):
         """Log the output."""
         if self.shell.logger.log_output:
             self.shell.logger.log_write(repr(result),'output')
 
     def finish_displayhook(self):
         """Finish up all displayhook activities."""
         IPython.utils.io.Term.cout.write(self.output_sep2)
         IPython.utils.io.Term.cout.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()
             result, result_repr = self.compute_result_repr(result)
             self.write_result_repr(result_repr)
             self.update_user_ns(result)
             self.log_output(result)
             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`
             try:
                 del self.shell.user_ns[key]
             except: pass
         self.shell.user_ns['_oh'].clear()
         
         if '_' not in __builtin__.__dict__:
             self.shell.user_ns.update({'_':None,'__':None, '___':None})
         import gc
         gc.collect() # xxx needed?
 

IPython/core/hooks.py

@@ -1,259 +1,263 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
 from IPython.core import ipapi
 ip = ipapi.get()
 
 def calljed(self,filename, linenum):
     "My editor hook calls the jed editor directly."
     print "Calling my own editor, jed ..."
     if os.system('jed +%d %s' % (linenum,filename)) != 0:
         raise TryNext()
 
 ip.set_hook('editor', calljed)
 
 You can then enable the functionality by doing 'import myiphooks'
 somewhere in your configuration files or ipython command line.
 """
 
 #*****************************************************************************
 #       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.
 #*****************************************************************************
 
 import os, bisect
 import sys
 
 from IPython.core.error import TryNext
 import IPython.utils.io
 
 # 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', 'synchronize_with_editor',
            'input_prefilter', 'shutdown_hook', 'late_startup_hook',
            'generate_prompt', 'show_in_pager','pre_prompt_hook',
            'pre_runcode_hook', 'clipboard_get']
 
 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.editor
     
     # marker for at which line to open the file (for existing objects)
     if linenum is None or editor=='notepad':
         linemark = ''
     else:
         linemark = '+%d' % int(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
     if os.system('%s %s %s' % (editor,linemark,filename)) != 0:
         raise TryNext()
 
 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.editor) != 'vim':
         self.hooks.editor(filename,linenum)
         return
     t = vim_quickfix_file()
     try:
         if os.system('vim --cmd "set errorformat=%f:%l:%c:%m" -q ' + t.name):
             raise TryNext()
     finally:
         t.close()
 
 
 def synchronize_with_editor(self, filename, linenum, column):
         pass
 
 
 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:
                 return cmd(*args, **kw)
             except TryNext, exc:
                 if exc.args or exc.kwargs:
                     args = exc.args
                     kw = exc.kwargs
         # if no function will accept it, raise TryNext up to the caller
         raise TryNext
                 
     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 __iter__(self):
         """ Return all objects in chain.
         
         Handy if the objects are not callable.
         """
         return iter(self.chain)
 
 
 def result_display(self,arg):
     """ Default display hook.
     
     Called for displaying the result to the user.
     """
     
     if self.pprint:
+        try:
         out = pformat(arg)
+        except:
+            # Work around possible bugs in pformat
+            out = repr(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.                
             IPython.utils.io.Term.cout.write('\n')
         print >>IPython.utils.io.Term.cout, out
     else:
         # 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 >>IPython.utils.io.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
 
 
 def generate_prompt(self, is_continuation):
     """ calculate and return a string with the prompt to display """
     if is_continuation:
         return str(self.displayhook.prompt2)
     return str(self.displayhook.prompt1)
 
 
 def show_in_pager(self,s):
     """ Run a string through pager """
     # raising TryNext here will use the default paging functionality
     raise TryNext
 
 
 def pre_prompt_hook(self):
     """ Run before displaying the next prompt
     
     Use this e.g. to display output from asynchronous operations (in order 
     to not mess up text entry)   
     """
     
     return None
 
 
 def pre_runcode_hook(self):
     """ Executed before running the (prefiltered) code in IPython """
     return None
 
 
 def clipboard_get(self):
     """ Get text from the clipboard.
     """
     from IPython.lib.clipboard import (
         osx_clipboard_get, tkinter_clipboard_get, 
         win32_clipboard_get
     )
     if sys.platform == 'win32':
         chain = [win32_clipboard_get, tkinter_clipboard_get]
     elif sys.platform == 'darwin':
         chain = [osx_clipboard_get, tkinter_clipboard_get]
     else:
         chain = [tkinter_clipboard_get]
     dispatcher = CommandChainDispatcher()
     for func in chain:
         dispatcher.add(func)
     text = dispatcher()
     return text