pythonic way to optimize access to imported value?

[Michael Hudson]

bokr at oz.net (Bengt Richter) writes:

> On Tue, 19 Nov 2002 11:47:57 GMT, Michael Hudson <mwh at python.net> wrote:
> 
> >bokr at oz.net (Bengt Richter) writes:
> >
> >> IOW, IMO there ought to be a way to do a temporary global-side-effect-free
> >> import and delete all traces of its having been done -- without restarting
> >> the interpreter or invoking a second interpreter instance.
> >
> >I don't think this is so hard:
> >
> >def load_file(file, modname):
>                ^^^^- tch, tch ;-)

It was fname at one point, but I thought that obscure...

> >    import new
> >    mod = new.module(modname)
> >    exec open(file).read() in mod.__dict__
> >    return mod
> >
> 
> But as Jeff pointed out, if there are any imports in your imported file,
> you have to encapsulate them too. So you need a temporary sandbox
> import that captures all the import action into a private container/space.

Hmm.  Yes.

> IIRC I saw some docs on sandboxing import. That's probably the trail
> to follow.

Yeah, just don't touch sys.modules in your __import__, I guess.

I wonder if 

    import new, __builtin__
    mod = new.module(modname)
    d = __builtin__.__dict__.copy()
    d['__import__'] = my_hook
    mod.__dict__['__builtins__'] = d
    exec open(file).read() in mod.__dict__
    return mod

would be a good start?

> Thanks for the reminders. BTW, is there a reason you preferred
> 
>     exec open(file).read() in mod.__dict__
> over
>     execfile(filepath, mod.__dict__)
> above?

Nope.

Cheers,
M.

-- 
  Exam invigilation - it doesn't come much harder than that, esp if
  the book you're reading turns out to be worse than expected.
                                  -- Dirk Bruere, sci.physics.research