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