Mercurial > hg > mercurial-crew-with-dirclash
diff mercurial/demandimport.py @ 3887:79e5a6e7c451
Merge with main
author | Brendan Cully <brendan@kublai.com> |
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date | Thu, 14 Dec 2006 13:49:33 -0800 |
parents | abaee83ce0a6 |
children | 3b628b5da9e9 f47afa2401a2 |
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new file mode 100644 --- /dev/null +++ b/mercurial/demandimport.py @@ -0,0 +1,104 @@ +# demandimport.py - global demand-loading of modules for Mercurial +# +# Copyright 2006 Matt Mackall <mpm@selenic.com> +# +# This software may be used and distributed according to the terms +# of the GNU General Public License, incorporated herein by reference. + +''' +demandimport - automatic demandloading of modules + +To enable this module, do: + + import demandimport; demandimport.enable() + +Imports of the following forms will be demand-loaded: + + import a, b.c + import a.b as c + from a import b,c # a will be loaded immediately + +These imports will not be delayed: + + from a import * + b = __import__(a) +''' + +_origimport = __import__ + +class _demandmod(object): + """module demand-loader and proxy""" + def __init__(self, name, globals, locals): + if '.' in name: + head, rest = name.split('.', 1) + after = [rest] + else: + head = name + after = [] + self.__dict__["_data"] = (head, globals, locals, after) + self.__dict__["_module"] = None + def _extend(self, name): + """add to the list of submodules to load""" + self._data[3].append(name) + def _load(self): + if not self._module: + head, globals, locals, after = self._data + mod = _origimport(head, globals, locals) + # load submodules + for x in after: + hx = x + if '.' in x: + hx = x.split('.')[0] + if not hasattr(mod, hx): + setattr(mod, hx, _demandmod(x, mod.__dict__, mod.__dict__)) + # are we in the locals dictionary still? + if locals and locals.get(head) == self: + locals[head] = mod + self.__dict__["_module"] = mod + def __repr__(self): + return "<unloaded module '%s'>" % self._data[0] + def __call__(self, *args, **kwargs): + raise TypeError("'unloaded module' object is not callable") + def __getattr__(self, attr): + self._load() + return getattr(self._module, attr) + def __setattr__(self, attr, val): + self._load() + setattr(self._module, attr, val) + +def _demandimport(name, globals=None, locals=None, fromlist=None): + if not locals or name in ignore or fromlist == ('*',): + # these cases we can't really delay + return _origimport(name, globals, locals, fromlist) + elif not fromlist: + # import a [as b] + if '.' in name: # a.b + base, rest = name.split('.', 1) + # if a is already demand-loaded, add b to its submodule list + if base in locals: + if isinstance(locals[base], _demandmod): + locals[base]._extend(rest) + return locals[base] + return _demandmod(name, globals, locals) + else: + # from a import b,c,d + mod = _origimport(name, globals, locals) + # recurse down the module chain + for comp in name.split('.')[1:]: + mod = getattr(mod, comp) + for x in fromlist: + # set requested submodules for demand load + if not(hasattr(mod, x)): + setattr(mod, x, _demandmod(x, mod.__dict__, mod.__dict__)) + return mod + +ignore = [] + +def enable(): + "enable global demand-loading of modules" + __builtins__["__import__"] = _demandimport + +def disable(): + "disable global demand-loading of modules" + __builtins__["__import__"] = _origimport +