[Python-Dev] win32 specific exception in the core?

[Mark Hammond]

As part of the registry work, Im toying with the idea of a standard "win32
exception" error in the Python core.

The reasons why I think a standard exception would be useful are:

* Single body of code that knows how to raise these exceptions.  Eg,
whenever an extension module needs to report that a Win32 API function
failed, they can use the core routines to create the exception object - just
like they can with OSError.  This ensures consistency, and saves each
extension module author from reinventing the wheel.

* No confusion about what exception Python programmers should catch.  In the
same way that "OSError" will be thrown any time the C runtime library fails,
the "Win32Error" exception will be thrown whenever a Win32 API function
(called directly) fails.

This has come up now that I am looking at a "win32reg" (or "_win32reg")
module for inclusion in Python 1.6.  It makes sense to me that rather than
creating specific exceptions for each new module of this ilk, we define a
single exception able to be shared by any core or 3rd party module that
needs it.

Ideally, this exception should derive from "EnvironmentError" - however,
this is pretty specific to the OSError mechanics.  The other alternatives
are to create a Win32Error that derives directly from "StandardError", or to
introduce an intermediate "PlatformError".

The Win32 extensions have been doing this for ages (ie, every win32*.pyd
module shares and raises the same exception object) and IMO it is a good
thing.  If we do go this route, the Win32 exceptions could also share this
exception object, which is, IMO, also a good thing (in the same way that
extension modules now can already raise OSError without a need to redefine
the semantics each time)

Does anyone have thoughts on this?  Is it a good thing or a bad thing?

Have-I-made-the-comparison-to-OSError-enough?-ly,

Mark.