I think we can separate the zipimport issue from the import hooks issue, but
only to an extent. *Some* hook need to be installed in import.c for zipimports
to work, but it doesn't neccesarily mean we must add a general new import hook
scheme *now*. But then again, it might be a *very* small step from enabling
zipimports to exposing the needed hook and have a clean and general solution.
It seems the majority doesn't like non-strings on sys.path, which to me is
understandable, especially if you take PYTHONPATH into consideration. Let's try
to focus on that.
Here's a minimal implementation idea that will allow .zip filenames on sys.path:
zipimporters = {} # a cache, private to import.c
for p in sys.path:
if p.endswith(".zip"):
z = zipimporters.get(p)
if z is None:
z = zipimporters[p] = zipimporter(p)
loader = z.find_module(name)
...etc...
else:
...builtin import...
This gets nessesarily more complex for packages, as now we also have to cater
for __path__ items of this form: "/path/to/my/archive.zip/packagedir". In this
case we need to create a "subimporter" of "/path/to/my/archive.zip" if only
because we don't want to reread the zip archive's file index. By now the
machinery needed can be written like so:
zipimporters = {} # a cache, private to import.c
def get_zipimporter(p):
if p.endswith(".zip"):
return zipimporter(p)
if not os.path.exists(p):
pos = p.rfind(".zip")
if pos > 0:
archive = p[:pos + 4]
subpath = p[pos + 5:] # skip initial sep
z = zipimporters[archive]
return z.subimporter(subpath)
for p in sys.path:
importer = zipimporters.get(p, -1)
if importer != -1:
importer = zipimporters[p] = get_importer(p)
if importer is not None:
loader = importer.find_module(name)
...etc...
else:
...builtin import...
And *this* can easily be rewritten in a slightly more general form:
path_importers = {} # exposed in sys
import_hooks = [get_zimpimporter] # exposed in sys
# get_zimpimporter() implementation left out for brevity
def get_importer(p):
for hook in import_hooks:
importer = hook(path)
if importer is not None:
return None
return None
for p in sys.path:
importer = path_importers.get(p, -1)
if importer != -1:
importer = path_importers[p] = get_importer(p)
if importer is not None:
loader = importer.find_module(name)
...etc...
else:
...builtin import...
Which, an observant reader might notice, is a stripped down version of Gordon's
iu.py, with s/shadowpath/path_importers/ and s/ownertypes/import_hooks/ and
without his metapath. (The metapath is a great idea, but I don't think it's
possible to do without a *major* rewrite of import.c. The rest is relatively
easy to do, in fact I've got it mostly working already.)
Just
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