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| -rw-r--r-- | Lib/pkgutil.py | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/Lib/pkgutil.py b/Lib/pkgutil.py new file mode 100644 index 0000000..4237371 --- /dev/null +++ b/Lib/pkgutil.py @@ -0,0 +1,78 @@ +"""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 |