[Python-Dev] Fix import errors to have data

[Delaney, Timothy C (Timothy)]

Tim Peters wrote:

> [Delaney, Timothy C (Timothy)]
>> OK - the problem as I see it is that a given module that exists, but
>> raises ImportError, only raises ImportError *once*, whereas it really
>> should raise ImportError every time
> 
> Jim's after something different, while the problem you're thinking
> about is more general than just ImportError.  When an import of an
> existing module fails for *any* reason, subsequent attempts to import
> the same module succeed.  For example,

Good point. This is the same as not wanting modules in an insane state
in sys.modules.

I've just gone back over Jim's original email, and it is a different
case being talked about there - specifically, determining if an
ImportError was thrown by the module that was specifically being
imported, rather than something it imports.

However, I don't see the utility of that. I definitely can't think of a
use case for it.

OTOH, ensuring that if *any* exception is thrown when importing a
module, it will not appear in sys.modules (and the exception is raised
each time you try to import) is IMO a very useful property, and I think
would solve what I think is Jim's issue at the root.

Tim Delaney