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"""Utilities to support packages."""
import os
import sys
def extend_path(path, name):
"""Extend a package's path.
Intended use is to place the following code in a package's __init__.py:
from pkgutil import extend_path
__path__ = extend_path(__path__, __name__)
This will add to the package's __path__ all subdirectories of
directories on sys.path named after the package. This is useful
if one wants to distribute different parts of a single logical
package as multiple directories.
It also looks for *.pkg files beginning where * matches the name
argument. This feature is similar to *.pth files (see site.py),
except that it doesn't special-case lines starting with 'import'.
A *.pkg file is trusted at face value: apart from checking for
duplicates, all entries found in a *.pkg file are added to the
path, regardless of whether they are exist the filesystem. (This
is a feature.)
If the input path is not a list (as is the case for frozen
packages) it is returned unchanged. The input path is not
modified; an extended copy is returned. Items are only appended
to the copy at the end.
It is assumed that sys.path is a sequence. Items of sys.path that
are not (unicode or 8-bit) strings referring to existing
directories are ignored. Unicode items of sys.path that cause
errors when used as filenames may cause this function to raise an
exception (in line with os.path.isdir() behavior).
"""
if not isinstance(path, list):
# This could happen e.g. when this is called from inside a
# frozen package. Return the path unchanged in that case.
return path
pname = os.path.join(*name.split('.')) # Reconstitute as relative path
# Just in case os.extsep != '.'
sname = os.extsep.join(name.split('.'))
sname_pkg = sname + os.extsep + "pkg"
init_py = "__init__" + os.extsep + "py"
path = path[:] # Start with a copy of the existing path
for dir in sys.path:
if not isinstance(dir, (str, unicode)) or not os.path.isdir(dir):
continue
subdir = os.path.join(dir, pname)
# XXX This may still add duplicate entries to path on
# case-insensitive filesystems
initfile = os.path.join(subdir, init_py)
if subdir not in path and os.path.isfile(initfile):
path.append(subdir)
# XXX Is this the right thing for subpackages like zope.app?
# It looks for a file named "zope.app.pkg"
pkgfile = os.path.join(dir, sname_pkg)
if os.path.isfile(pkgfile):
try:
f = open(pkgfile)
except IOError, msg:
sys.stderr.write("Can't open %s: %s\n" %
(pkgfile, msg))
else:
for line in f:
line = line.rstrip('\n')
if not line or line.startswith('#'):
continue
path.append(line) # Don't check for existence!
f.close()
return path
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