[Python-Dev] Can we limit the effects of module execution tosys.modules? (was Fix import errors to have data)

[Robert Brewer]

Barry Warsaw wrote:
> I wonder if we can't define a protocol for executing code at module
> scope, but only if the module is successfully imported.  The idea is
> that we'd define something like an __init__() for modules that would
> only get executed after the module was imported, and if there were any
> failures in importing, it wouldn't get called.
> 
> We'd have to handle chained imports though.  I haven't thought through
> all the implications of that but I can imagine it will get messy.  You
> probably don't want to execute any __init__()'s until all imports are
> finished, you probably want to execute them in the order you saw them,
> and you don't want any exceptions raised in __init__()'s to 
> be deemed an ImportError worthy of sys.modules deletion.

I'll just note that many large projects do this sort of thing on their
own already, because the order of imports/execution is both critical and
highly project-specific. If such an __init__() were to be developed, the
primary benefit IMO would be reducing many of those ad-hoc schemes to
"one way to do it", which might be worth the effort even if it doesn't
"fix" the original issue.


Robert Brewer
MIS
Amor Ministries
fumanchu at amor.org