[Python-Dev] PEP 273: Import Modules from Zip Archives

[Gordon McMillan]

[Gordon]
> > After extensive use of imputil (which puts objects on
> > sys.path), I think we might as well make it official that
> > sys.path is a list of strings.
[Guido]
> Interesting.  So you think imputil is wrong to put objects there?
> Why?  (Not arguing, just interested in your experience.)

Too much code (some left in the std lib) says:
for d in sys.path:
  os.path.join(d, ...) 
and that's the line that barfs. It doesn't barf if d is a string.

[Gordon]
> > DIfferent spellings of the same path are possible in a 
> > filesystem, but not in a dictionary. A bit of "harmless" 
> > tweaking of sys.path could render an archive unreachable.
> 
> Hm, wouldn't the archive just be opened a second time?  Or do I
> misundestand you?

Without seeing the C code, I don't know if it will open it a 2nd 
time. I keep an open file for each archive, but I'm careful that 
however it's spelled, I only open the archive once. Jim is 
apparently closing the file, so opening a 2nd is probably not 
as painful. OTOH an open / seek for each satisfied import is 
relatively expensive (though still cheaper than a fs import).
 
> > [zlib must be available at start]
> > I'll agree, and agree with Guido that the coolest thing would
> > be to make zlib standard.
> 
> But we'd have to make sure it's statically linked.  (Fortunately,
> we already link it statically on Windows.)

So to avoid statically linking it twice, I assume zlib would be a 
mandatory builtin.
 
[Gordon]
> > Personally, I think package support stretched import.c to it's
> > monolithic limits and it's high time the code was refactored to
> > make it sanely extensible.
> 
> Yes -- this has been on my TODO list for ages.  But who's gonna
> DO it?

I published iu4 which I think comes very close to the "right" 
model. If it's close enough, I'll download 2.2 and see if I can 
make those into new style object subclasses[1].

- Gordon

[1] As an app developer, I usually have to look backwards, not 
forwards. I've got 6 machines, each with at least 2 Pythons, 
so I no longer deal with betas :-(. Even when they have cool 
things like generators and subclassable C types.