The Py Manual

Py - Served Fresh Daily

Author: Patrick K. O'Brien
Organization: Orbtech
Date: 2004-04-15
Revision: 26789



This document will show you how to use the Py programs and the Py library of Python source code modules. Py is the new name for the project that began as PyCrust. Py is officially part of wxPython, and includes PyCrust, so PyCrust is no longer distributed separately.

Developer Reference

Source code documentation for developers is available at:

What is Py?

Besides being a delicious dessert, Py is the name for a collection of whimsically-named Python programs and modules that began as the PyCrust project. So Py is really several things: a set of standalone programs, including the original PyCrust program, a library of Python source code modules that can be used in your own programs, and as many examples of bad "pie" puns as I can come up with. (If you're going to do something, you might as well do it all the way, right?) Py uses Python and wxPython, so it works equally well on Windows, Linux and Mac OS X.

PyCrust is dead! Long live Py!

This project began with a program I created called PyCrust - an interactive, graphical Python shell, developed using the wxPython GUI toolkit. For about two years, PyCrust was hosted on SourceForge. Shortly after I created PyCrust, the wxPython folks started including it in their distribution. As the PyCrust project grew, it reached a point where I thought the original PyCrust name was too confining. I was using the PyCrust code base to develop programs that weren't just Python shells any more.

Around that same time, the wxPython folks asked me if I'd be willing to move all my wxPython-related projects into the wxPython CVS repository, and become part of the wxPython/wxWidgets developer team. I decided the time was right to restructure the PyCrust project. During the move, the PyCrust package was renamed to "py" (lowercase "p") and the collection of programs and modules as a whole became known as "Py" (with a capital "P").

The original goal of PyCrust was to be the best interactive, graphical Python shell (of course, I claimed it was the "flakiest" Python shell). And that was all I wanted it to be. But little by little I found myself developing a wider variety of tools for wxPython applications. Eventually I'll create a debugger (PySlice, perhaps) and whatever else is needed to one day become a complete wxPython application development environment (PyFactory?). In the mean time, PyCrust is still the flakiest Python shell, and the other Py programs are equally tasty.

At this point, Py has standalone programs that include Python code editors (PyAlaCarte and PyAlaMode), interactive Python shells (PyCrust and PyShell), and a runtime wrapper (PyWrap). The runtime wrapper utility provides you with runtime introspection capabilities for your wxPython programs without having to include PyCrust or PyShell in your program, and without having to alter one line of your source code.

Py also contains a collection of modules that you can use in your own wxPython applications to provide similar services, either for your own use during development, or as an interface for users of your programs. These modules are the same ones used by all the Py programs.

Py standalone programs

These are the standalone applications in the Py collection:


PyAlaCarte is a Python source code editor. It is designed to have a simple, single-file interface. As a standalone application, it is good for simple, short editing tasks. But it is really meant to be more of an example of how to embed the Py editor into a wxPython application.


PyAlaMode is a Python source code editor.


PyCrust is an interactive, Python shell. But it's more than just a shell. It includes a tabbed notebook containing a namespace tree (PyFilling), and several other things.


PyFilling is a namespace viewer. It isn't really useful as a standalone program, but it does illustrate how to make use of the underlying filling module.


PyShell is an interactive, Python shell. It shares the same base code as PyCrust, but doesn't have any of the extra features that appear in the PyCrust notebook interface.


PyShell running on Mandrake Linux.


PyWrap is a runtime utility that lets you run an existing wxPython program with a PyCrust frame at the same time. Inside the PyCrust shell namespace, the local variable app is assigned to your application instance. In this way you can introspect your entire application within the PyCrust shell, as well as the PyFilling namespace viewer.

Py modules

Py was designed to be modular. That means graphical code is kept separate from non-graphical code, and many of the Py modules can be used by other programs. Likewise, other programs can supply some of the modules needed by Py. For example, you could supply a customized interpreter module and plug it in to the PyCrust standalone application. As long as it supports the minimum functionality required, PyCrust will work just as well with your interpreter as with its default interpreter.

Projects using Py

History of changes

This section lists all the changes that have been made to the Py programs and modules, since the beginning.

0.9.5 (12/23/2005)

Applied a series of enhancments by Franz Steinaeusler, Adi Sieker, and Sebastian Haase, up until their 7-31-2005 version. (Their next version broke some existing functionality, and added some confusing hacks, and I didn't feel that the incremental gains were worth the loss at that point so I stopped at 7-31-2005.)

Their changes include the following:

  • The Autocomplete and Calltip windows can now be opened manually with Ctrl-Space and Ctrl-Shift-Space.
  • In the stand alone PyCrust app the various option settings, window size and position, and etc. are saved and restored at the next run.
  • Added a help dialog bound to the F1 key that shows the key bindings.
  • Added a new text completion function that suggests words from the history. Bound to Shift-Return.
  • F11 will toggle the maximized state of the frame.
  • switched to Bind() from wx.EVT_*().
  • Display of line numbers can be toggled.
  • F12 toggles a "free edit" mode of the shell buffer. This mode is useful, for example, if you would like to remove some output or errors or etc. from the buffer before doing a copy/paste. The free edit mode is designated by the use of a red, non-flashing caret.
  • Ctrl-Shift-F will fold/unfold (hide/show) the selected lines.

On top of these changes I (Robin Dunn) added the following:

  • General code cleanup and fixes.
  • Use wx.StandardPaths to determine the location of the config files.
  • Remove Orbtech attributions from the UI, they've been there long enough.
  • Use wx.SP_LIVE_UPDATE on crust and filling windows.
  • Extended the saving of the config info and other new features to the PyShell app too. Additionally, other apps that embed a PyCrust or a PyShell can pass their own wx.Config object and have the Py code save/restore its settings to/from there.
  • All of the classes with config info get an opportunity to save/load their own settings instead of putting all the save/load code in one place that then has to reach all over the place to do anything.
  • Enable editing of the startup python code, which will either be the file pointed to by PYTHONSTARTUP or a file in the config dir if PYTHONSTARTUP is not set in the environment.
  • Added an option to skip the running of the startup code when PyShell or PyCrust starts.
  • PyCrust adds a pp(item) function to the shell's namespace that pretty prints the item in the Display tab of the notebook. Added code to raise that tab when pp() is called.
  • Added an option for whether to insert text for function parameters when popping up the call tip.
  • Added Find and Find-Next functions that use the wx.FindReplaceDialog.

0.9.4 (1/25/2004 to //2004)

Removed wxd decorators in favor of new SWIG-generated docstrings.

Removed docs tabs from crust interface: * wxPython Docs * wxSTC Docs

Fixed Calltip tab refresh problem on Windows.

shell.autoCompleteAutoHide added with default of False.

Changed default namespace of Shell to __main__.__dict__, instead of an empty dictionary.

0.9.3 (9/25/2003 to 1/24/2004)

Fun and games with dynamic renaming. Details of any other changes were lost in the confusion. I'll try to do better in the future.

0.9.2 (5/3/2003 to 9/25/2003)

Changed to the new prefix-less "wx" package:

import wx

instead of:

from wxPython import wx

Fixed typo in

if __name__ == '__main__':

should have been:

if __name__ == '__main__':

Added pretty-print Display tab to Crust, based on suggestion from Jason Whitlark.

Improved Can* checks in EditWindow, since STC is too lenient, particularly when it is set to read-only but returns True for CanPaste() (seems like an STC bug to me):

def CanCopy(self):
    """Return True if text is selected and can be copied."""
    return self.GetSelectionStart() != self.GetSelectionEnd()

def CanCut(self):
    """Return True if text is selected and can be cut."""
    return self.CanCopy() and self.CanEdit()

def CanEdit(self):
    """Return True if editing should succeed."""
    return not self.GetReadOnly()

def CanPaste(self):
    """Return True if pasting should succeed."""
    return stc.StyledTextCtrl.CanPaste(self) and self.CanEdit()

0.9.1 (3/21/2003 to 5/2/2003)

PyCrust is dead! Long live Py!

  • Renamed PyCrust package to py.
  • Moved code to wxPython's CVS repository.

Fixed bug in on introspecting objects occurring immediately after a secondary prompt, like this:

>>> l = [1, 2, 3]
>>> for n in range(3):
...     l.  <-- failed to popup autocomplete list

Added documentation files:

  • PyManual.txt
  • wxPythonManual.txt
  • wxPythonPackage.txt
  • wxPythonExamples.txt

Added PyAlaMode and PyAlaCarte code editors.

Major refactoring to support editor and shell from the same base.

Renamed program files:

  • to
  • to
  • to
  • to

Removed disabling of autocomplete for lists of 2000 items or more. The current implementation of wxSTC can now handle lists this big.

Improved handling of sys.path to mimic the standard Python shell.

0.9 (2/27/2003 to 3/20/2003)

Added fontIncrease, fontDecrease, fontDefault signals, receivers and keybindings:

Ctrl+]            Increase font size.
Ctrl+[            Decrease font size.
Ctrl+=            Default font size.

Continued enhancement of the decorator capability to provide better documentation and docstrings for wxPython classes and functions.

Introduced new tabbed interface:

  • Namespace
  • Calltip
  • Session
  • Dispatcher
  • wxPython Docs
  • wxSTC Docs

Filling.tree now expands tuples as well as lists. (It should have done this all along, I just never noticed this omission before.)

Added this True/False test to all modules:

except NameError:
    True = 1==1
    False = 1==0

Added wxd directory with decoration classes.

0.8.2 (1/5/2003 to 2/26/2003)

Wrapped sys.ps1, sys.ps2, and sys.ps3 in str(). (Thanks, Kieran Holland.)

Fixed minor things found by PyChecker.

Changed locals to use __main__.__dict__ and added code to clean up the namespace, making it as close to the regular Python environment as possible. This solves the problem of pickling and unpickling instances of classes defined in the shell.

Made shell.PasteAndRun() a little more forgiving when it finds a ps2 prompt line with no trailing space, such when you copy code from a web page.

Improved autocomplete behavior by adding these to shell:

self.AutoCompStops(' .,;:([)]}\'"\\<>%^&+-=*/|`')

Added decor directory,,, and These all serve the purpose of adding docstrings to existing wxPython classes, in particular the wxStyledTextCtrl.

Added, a command line utility for running a wxPython app with additional runtime-tools loaded, such as PyCrust (the only tool at this point).

Flushed the clipboard Cut/Copy operations so that selections will exist in the clipboard even after PyCrust has been closed.

Improved the suppression of docstrings for simple data types appearing in the namespace viewer.

Better handling of autocompletion with numeric types; no autocompletion when typing a dot after an integer. If the autocompletion is desired, type a space before the dot:

func = 3 .

More Filling!!! The namespace tree is now dynamically updated.

0.8.1 (12/20/2002 to 12/25/2002)

Improved keyboard handling with Autocomplete active. You can now use Enter as well as Tab to select an item from the list.

Disabled autocomplete for lists of 2000 items or more. The current implementation of wxSTC can't handle lists this big.

Changed filling to always display docstrings for objects. This is useful for objects whose docstrings have been decorated, rather than coming directly from the source code. (Hmmm. Sounds like someone is doing some decorating. I wonder where that would be helpful? <wink>)

Fixed handling of icon. Added file.

0.8 (10/29/2002 to 12/16/2002)

Added "help" to startup banner info.

Made all wx and stc imports explicit. No more import *.

Replaced use of the wx module's true and false with Python's True and False.

Changed introspect.getRoot() to use tokenize module. This does a slightly better job than the previous parsing routine and the code is clearer.

Improved handling of whitespace and empty types during introspection.

Fixed cut/copy clipboard problem under Linux. (Robin Dunn rocks!!!)

Added shell.about() which works like this:

>>> shell.about()
PyCrust Version: 0.8
Shell Revision: 1.80
Interpreter Revision: 1.15
Python Version: 2.2.2
wxPython Version:
Platform: linux2

Added copy plus and paste plus to shell menu.

Moved shell menu from to

Added sys.stdin.readlines() support.

Added time.sleep() in readline() and OnIdle() event handler to free up the CPU.

0.7.2 (2/22/2002 to 8/27/2002)

Tweaked getAttributeNames() to pick up a few more attributes:

'__bases__', '__class__', '__dict__', '__name__', 'func_closure',
'func_code', 'func_defaults', 'func_dict', 'func_doc',
'func_globals', 'func_name'

Added a tests directory and unit tests.

Improved support for empty types in the shell: [], () and {} as far as when call tips and autocompletion are available.

Added support for the other triple string - ''''''.

Refactored to improve testability.

Improved call tips for unbound methods by leaving the "self" parameter, since unbound methods require an instance be passed.

Fixed call tip bug where a tip was displayed when a "(" was typed after an object that wasn't callable.

Fixed getAllAttributeNames when str(object) fails.

Added brace highlighting. (Thank you, Kevin Altis.)

Fixed problem displaying unicode objects in PyFilling.

Changed how checks for expandable objects. Lists are now expandable objects.

Made the key handling more robust when there is an active text selection that includes text prior to the last primary prompt. Thanks to Raul Cota for pointing this out.

Fixed wxSTC problem with brace highlighting and non-us keyboards. (Thank you for the patch, Jean-Michel Fauth.)

Added busy = wxBusyCursor() to key points in shell and filling.

Added OnCloseWindow handler to ShellFrame and CrustFrame.

Default to SetWrapMode(1) for shell and namespace viewer.

Added shell.wrap() and shell.zoom().

Added autoCompleteKeys hooks for Raul Cota.

Cleaned up various little key handling bugs.

Changed input methods to get values from shell, rather than dialog boxes. Renamed readIn to readline and readRaw to raw_input.

0.7.1 (12/12/2001 to 2/21/2002)

Fixed OnChar() issues effecting European keyboards, as reported by Jean-Michel Fauth.

Fixed issue with xmlrpc objects reported by Kevin Altis.

Fixed some introspect/PyFilling issues with regard to Python 2.2.

Fixed font background color as reported by Keith J. Farmer. (Thanks)

Fixed problem with call tips and autocompletion inside multiline commands as report by Kevin Altis.

Improved OnKeyDown handling of cut/copy/paste operations based on feedback from Syver Enstad. (Thanks)

Added a method to display some help info.

Changed sort of items in the namespace viewer to case insensitive.

Changed attributes.sort(lambda x, y: cmp(x.upper(), y.upper())) in advance of an upcoming fix to an autocompletion matching bug in wxSTC.

Improved support for ZODB by allowing namespace drilldown into BTrees.

Added shell.PasteAndRun() to support pasting multiple commands into the shell from the clipboard. Ctrl+Shift+V or v.

Enter now always processes a command (or copies down a previous one.) To insert a line break, press Ctrl+Enter.

Escape key clears the current, unexecuted command.

History retrieval changed to replace current command. Added new keys to insert from history - Shift+Up and Shift+Down.

Better call tips on objects with __call__ methods.

Improved call tip positioning calculation.

0.7 (10/15/2001 to 12/11/2001)

Changed how command history retrieval functions work. Added Alt-P, Alt-N as keybindings for Retrieve-Previous, Retrieve-Next.

Added full support for multi-line commands, similar to IDLE.

Changed introspect.getAttributeNames() to do a case insensitive sort.

Changed Cut/Copy/Paste to deal with prompts intelligently. Cut and Copy remove all prompts. Paste can handle prompted or not-prompted text.

Added CopyWithPrompts() method attached to Ctrl-Shift-C for those times when you really do want all the prompts left intact.

Improved handling of the shell's read-only zone.

Changed CrustFrame.__init__ parameter spec to include all parameters allowed by a wxFrame.

Changed FillingText to be read-only.

Renamed to to eliminate package/module name conflicts that kept you from doing from PyCrust import shell inside files located in the PyCrust directory.

Renamed to and to to maintain consistency.

Removed the __date__ property from all modules.

Fixed bug in introspect.getCallTip(), reported by Kevin Altis.

0.6.1 (9/19/2001 to 10/12/2001)

Changed to always position to the end of existing text, as suggested by Raul Cota.

Changed introspect.getAllAttributeNames() to break circular references in object.__class__, which occurs in Zope/ZODB extension classes.

Changed filling.FillingTree.getChildren() to introspect extension classes.

Fixed minor bugs in introspect.getCallTip() that were interfering with call tips for Zope/ZODB extension class methods.

In preparation for wxPython 2.3.2, added code to fix a font sizing problem. Versions of wxPython prior to 2.3.2 had a sizing bug on Win platform where the font was 2 points larger than what was specified.

Added a hack to introspect.getAllAttributeNames() to "wake up" ZODB objects that are asleep - in a "ghost" state. Otherwise it returns incomplete info.

0.6 (8/21/2001 to 9/12/2001)

Added and and can now be run standalone, as well as

Added and moved some code from to it.

Added command history retrieval features submitted by Richie Hindle.

Changed shell.write() to replace line endings with OS-specific endings. Changed and to use os.linesep in strings having hardcoded line endings.

Added shell.redirectStdin(), shell.redirectStdout() and shell.redirectStderr() to allow the surrounding app to toggle requests that the specified sys.std* be redirected to the shell. These can also be run from within the shell itself, of course.

The shell now adds the current working directory "." to the search path:

sys.path.insert(0, os.curdir)

Added support for distutils installations.

0.5.4 (8/17/2001 to 8/20/2001)

Changed default font size under Linux to:

'size'   : 12,
'lnsize' : 10,

Changed Shell to expect a parameter referencing an Interpreter class, rather than an intepreter instance, to facilitate subclassing of Interpreter, which effectively broke when the Editor class was eliminated.

Fixed, which had been broken by previous changes.

Created InterpreterAlaCarte class as an example for use in the demo.

Split into and in anticipation of

0.5.3 (8/16/2001)

Added patch to to fix wxPython bug:

wxID_SELECTALL = NewId() # This *should* be defined by wxPython.

0.5.2 (8/14/2001 to 8/15/2001)

Shortened module names by dropping "PyCrust" as a prefix.

Changed version to VERSION in version module.

Added Options menu to PyCrust application.

Eliminated the Editor class (and editor module) by merging with Shell. This means that Shell "is a" wxStyledTextCtrl rather than "has a". There just wasn't enough non-gui code to justify the separation. Plus, Shell will be much easier for gui toolkits/designers to deal with now.

0.5.1 (8/10/2001 to 8/14/2001)

Added introspect module.

Moved some functionality from PyCrustInterp to introspect.

Changed introspect.getRoot() to no longer remove whitespace from the command. This was a remnant of a previous approach that, when left as part of the current approach, turned out to be a really bad thing.

Changed introspect.getRoot() to allow commands of '', "", """""", [], (), and {} to pass through. This allows you to type them, followed by a dot, and get autocomplete options on them.

Changed introspect.getRoot() to identify some situations where strings shouldn't be considered roots. For example:

>>> import PyCrust  # To illustrate the potential problem.
>>> len('')

Typing the dot at the end of "PyCrust" in the second line above should NOT result in an autocompletion list because "PyCrust" is part of a string in this context, not a reference to the PyCrust module object. Similar reasoning applies to call tips. For example:

>>> len('dir(')

Typing the left paren at the end of "dir" should NOT result in a call tip.

Both features now behave properly in the examples given. However, there is still the case where whitespace precedes the potential root and that is NOT handled properly. For example:

>>> len('this is a dir(')


>>> len('This is')

More code needs to be written to handle more complex situations.

Added locals=None parameter to Shell.__init__().

Added support for magic attribute retrieval. Users can change this with:

>>> shell.editor.autoCompleteIncludeMagic = 0

Added the ability to set filters on auto completion to exclude attributes prefixed with a single or double underscore. Users can exclude one or the other or both with:

>>> shell.editor.autoCompleteExcludeSingle = 1
>>> shell.editor.autoCompleteExcludeDouble = 1

0.5 (8/8/2001)

Mostly just a final version change before creating a release.

0.4 (8/4/2001 to 8/7/2001)

Changed version/revision handling.

Fixed bugs.

0.3 (8/2/2001 to 8/3/2001)

Removed lots of cruft.

Added lots of docstrings.

Imported to CVS repository at SourceForge.

Added call tips.

0.2 (7/30/2001 to 8/2/2001)

Renamed several files.

Added command autocompletion.

Added menus to File, Edit and Help.

Added sample applications:,, and

0.1 (7/1/2001 to 7/19/2001)

Added basic syntax coloring much like Boa.

Added read-only logging much like IDLE.

Can retrieve a previous command by putting the cursor back on that line and hitting enter.

Stdin and raw_input operate properly so you can now do help() and license() without hanging.

Redefined "quit", "exit", and "close" to display a better-than-nothing response.

Home key honors the prompt.

Created SourceForge account, but nothing was posted.

In the beginning, there was pie... (7/1/2001)

Blame it all on IDLE, Boa and PythonWin. I was using all three, got frustrated with their dissimilarities, and began to let everyone know how I felt. At the same time, Scintilla looked like an interesting tool to build a shell around. And while I didn't receive much in the way of positive feedback, let alone encouragement, I just couldn't let go of the idea of a Scintilla-based Python shell. Then the PythonCard project got to the point where they were talking about including a shell in their development environment. That was all the incentive I needed. PyCrust had to happen...