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68 lines
2.3 KiB
Python
68 lines
2.3 KiB
Python
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# This module provides standard support for "packages".
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#
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# The idea is that large groups of related modules can be placed in
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# their own subdirectory, which can be added to the Python search path
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# in a relatively easy way.
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#
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# The current version takes a package name and searches the Python
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# search path for a directory by that name, and if found adds it to
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# the module search path (sys.path). It maintains a list of packages
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# that have already been added so adding the same package many times
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# is OK.
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#
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# It is intended to be used in a fairly stylized manner: each module
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# that wants to use a particular package, say 'Foo', is supposed to
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# contain the following code:
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#
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# from addpack import addpack
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# addpack('Foo')
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# <import modules from package Foo>
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#
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# Additional arguments, when present, provide additional places where
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# to look for the package before trying sys.path (these may be either
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# strings or lists/tuples of strings). Also, if the package name is a
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# full pathname, first the last component is tried in the usual way,
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# then the full pathname is tried last. If the package name is a
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# *relative* pathname (UNIX: contains a slash but doesn't start with
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# one), then nothing special is done. The packages "/foo/bar/bletch"
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# and "bletch" are considered the same, but unrelated to "bar/bletch".
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#
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# If the algorithm finds more than one suitable subdirectory, all are
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# added to the search path -- this makes it possible to override part
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# of a package. The same path will not be added more than once.
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#
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# If no directory is found, ImportError is raised.
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_packs = {} # {pack: [pathname, ...], ...}
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def addpack(pack, *locations):
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import os
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if os.path.isabs(pack):
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base = os.path.basename(pack)
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else:
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base = pack
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if _packs.has_key(base):
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return
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import sys
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path = []
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for loc in _flatten(locations) + sys.path:
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fn = os.path.join(loc, base)
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if fn not in path and os.path.isdir(fn):
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path.append(fn)
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if pack != base and pack not in path and os.path.isdir(pack):
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path.append(pack)
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if not path: raise ImportError, 'package ' + pack + ' not found'
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_packs[base] = path
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for fn in path:
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if fn not in sys.path:
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sys.path.append(fn)
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def _flatten(locations):
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locs = []
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for loc in locations:
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if type(loc) == type(''):
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locs.append(loc)
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else:
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locs = locs + _flatten(loc)
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return locs
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