[Python-Dev] Exception Reorg PEP revised yet again

[Brett Cannon]

On 8/12/05, Thomas Heller <theller at python.net> wrote:
> Brett Cannon <bcannon at gmail.com> writes:
> 
> > On 8/10/05, Raymond Hettinger <raymond.hettinger at verizon.net> wrote:
> >> > > Then I don't follow what you mean by "moved under os".
> >> >
> >> > In other words, to get the exception, do ``from os import
> >> > WindowsError``.  Unfortunately we don't have a generic win module to
> >> > put it under.  Maybe in the platform module instead?
> >>
> >> -1 on either.  The WindowsError exception needs to in the main exception
> >> tree.  It occurs in too many different modules and applications.  That
> >> is a good reason for being in the main tree.
> >>
> >
> > Where is it used so much?  In the stdlib, grepping for WindowsError
> > recursively in Lib in 2.4 turns up only one module raising it
> > (subprocess) and only two modules with a total of three places of
> > catching it (ntpath once, urllib twice).  In Module, there are no
> > hits.
> >
> 
> I don't know how you've been grepping, but the Python api functions to
> raise WindowsErrors are named like PyErr_SetFromWindowsErr() or so.
> 

Forgot to add that to the grep statement after I discovered that.

> Typically, WindowsErrors are raised when Win32 API functions fail.
> In the core extension modules, I find at least mmapmodule.c,
> posixmodule.c, _subprocess.c, and _winreg.c raising them.  It may be a
> bit hidden, because the docs for _winreg mention only EnvironmentError,
> but they are wrong:
> 
> C:\>py
> Python 2.5a0 (#60, Jul  4 2005, 19:53:27) [MSC v.1310 32 bit (Intel)] on win32
> Type "help", "copyright", "credits" or "license" for more information.
> >>> import _winreg
> >>> _winreg.OpenKey(_winreg.HKEY_CLASSES_ROOT, "blah")
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
> WindowsError: [Errno 2] Das System kann die angegebene Datei nicht finden
> >>>
> 
> >> If the name bugs you, I would support renaming it to PlatformError or
> >> somesuch.  That would make it free for use with Mac errors and Linux
> >> errors.  Also, it wouldn't tie a language feature to the name of an
> >> MS product.
> >>
> >
> > I can compromise to this if others prefer this alternative.  Anybody
> > else have an opinion?
> 
> Win32 has the FormatError() api to convert error codes into descriptions
> - these descriptions are very useful, as are the error codes when you
> catch errors in client code.
> 
> I would say as long as the Python core contains win32 specific modules
> like _winreg WindowsError should stay.  For the name, I have no
> preference but I see no need to change it.
> 

OK, then it will just stay as-is.

People can expect an updated PEP sometime this weekend.

-Brett