[Python-Dev] Fix import errors to have data

[Phillip J. Eby]

At 11:14 PM 8/2/04 -0400, Tim Peters wrote:
>[Christian Tismer]
>..
> > Yes, but I think you are almost an atom's distance apart off of
> > the final solution. Grab it!
>
>If you mean this:
>
> >>> Maybe it could be as simple as saving a snapshot of
> >>> sys.modules whenever importing of a module is begun,
> >>> and if execution of its body doesn't complete, restoring
> >>> the snapshot?
>
>then no, that's a long way off in CPython.  There's no choke point for
>when importing begins, or for when importing ends, and even
>__builtin__.__import__ is routinely replaced.  Guido latched on to the
>only choke point there is:  sooner or later, every import gimmick
>worthy of the name has to execute "the module's" code, whether it be
>direct import from Python, directly via C API calls, implicit package
>__init__.py imports, imports arranged via magical importers (like the
>.zip importer), etc.  So that's what the patch targeted:  there's one
>routine that executes a module's initialization code, all imports go
>thru it eventually, and that's the routine that now removes the
>module's name from sys.modules if the initialization code barfs.

It's worse than that...  'ihooks' and 'imputil', for example, both do:

     exec code in module.__dict__

so they'd need to be changed to support this fix as well.  (Not to mention 
any third-party import hooks...)