[Python-Dev] Dropping __init__.py requirement for subpackages

["Martin v. Löwis"]

Thomas Wouters wrote:
> Indeed! I hadn't realized that, although I might've if I'd been able to
> find where Modules is put on sys.path. And, likewise, I would do as you
> suggest (which feels like the right thing) if I could only find out
> where Modules is put on sys.path :) I don't have time to search for it
> today nor, probably, this weekend (which is a party weekend in the
> Netherlands.) I'll get to it eventually, although a helpful hint from an
> old-timer who remembers as far back as Modules/Setup would be welcome. :)

With some debugging, I found it out: search_for_exec_prefix looks for
the presence of Modules/Setup; if that is found, it strips off /Setup,
leaving search_for_exec_prefix with -1. This then gets added to sys.path
with

        /* Finally, on goes the directory for dynamic-load modules */
        strcat(buf, exec_prefix);

I wasn't following exactly, so I might have mixed something up, but...
it appears that this problem here comes from site.py adding the
build directory for the distutils dynamic objects even after
Modules. The site.py code is

# XXX This should not be part of site.py, since it is needed even when
# using the -S option for Python.  See http://www.python.org/sf/586680
def addbuilddir():
    """Append ./build/lib.<platform> in case we're running in the build dir
    (especially for Guido :-)"""
    from distutils.util import get_platform
    s = "build/lib.%s-%.3s" % (get_platform(), sys.version)
    s = os.path.join(os.path.dirname(sys.path[-1]), s)
    sys.path.append(s)

I would suggest fixing #586680: Add build/lib.* before adding
dynamic-load modules, by moving the code into Modules/getpath.c.
You should be able to use efound < 0 as an indication that this
is indeed the build directory.

Regards,
Martin