[Python-Dev] Fix import errors to have data

[Jim Fulton]

Neal Norwitz wrote:
> On Tue, Jul 27, 2004 at 12:39:22PM -0400, Jim Fulton wrote:
> 
>>Tim Peters wrote:
>>
>>>[Jim Fulton]
>>>
>>>
>>>>No, it won't.  For example, suppose foo imports B. B tries to import
>>>>C, but fails.  B is now broken, but it is still importable.  Actually,
>>>>both foo and B can be imported without errors, even though they are
>>>>broken.
>>
>>>Then you're proposing a way for a highly knowledgable user to
>>>anticipate, and partially worm around,  that Python leaves behind
>>>insane module objects in sys.modules. 
>>
>>No.  I'm proposing a way for a Python developer to detect the
>>presence or absence of a module.
>>
>>Hm, perhaps it would be better to provide an API (if there isn't one
>>already) to test whether a module is present.
> 
> 
> Another possibility could be to add a ChainedImportError (or
> SubImportError?) which would derive from ImportError.  The module
> which imports a broken module would get the normal ImportError.  If
> the module doesn't catch the exception, it would get converted to this
> new type of ImportError.
> 
> I don't know how easy this would be to implement, but I think it
> would solve Jim's problem and perhaps be easier to deal with?

An even simpler aproach would be to have a ModuleNotFound error
that extends ImportError and gets raised if the module can't
be found.

Jim

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