Movable Python: The Portable Python Distribution

Movable Python Issues

Things to be Aware of

Python on a Stick


This page is the list of known issues with Movable Python. They aren't bugs, but potential problems with Movable Python and things you should be aware of when running programs.

Most of them relate to using third party extensions.

Some of the issues here include slight differences between the Movable Python environment and the normal Python environment. In rare cases these can affect the running of applications.

As issues (and fixes) are discovered they will be documented here. If you think you have discovered a problem, raise it on the Mailing List and we'll search for a solution.

The Issues

  • IPython plays very badly with psyco. This is because psyco prevents local variables in functions being accessed. Try entering interactive mode and typing 'import psyco', followed by 'psyco.full()' to see what I mean. Movable Python now detects when psyco is in operation and uses the alternative (less featured) interactive mode instead.
  • sys.executable and sys.prefix (and sys.exec_prefix) are different for scripts run by Movable Python than they would be for a script run by normal python. You can manually alter these values in customize.py if you need to. (Obviously modifying sys.executable isn't wise.)
  • Some programs rely on the executable being called python.exe (or pythonw.exe). Occassionally these names are hardwired on the code (which ought to use sys.executable).
  • Some code relies on a certain directory structure of Python installations - for example the existence of a site-packages folder. This obviously doesn't work with Movable Python.
  • sys.frozen exists - which it wouldn't do for a normal python script. This can be an issue for some packages (like the win32 packages) which will assume they are in a py2exe environment (and directory structure). See win32ext for more details on this issue.
  • '-' will generate an error log if you try it with movpyw.exe (quite rightly so !)
  • import statements in .pth files aren't supported. (Setuptools uses these.)
  • The normal distributions don't use bytecode optimisation or compress the library.zip.
  • Saving a config file overwrites comments in the original.
  • The section for handling command line options doesn't deal with duplicate entries.

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Page last modified Wed Jul 16 02:31:31 2008.

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