langhelpers.py 文件源码

def monkeypatch_proxied_specials(into_cls, from_cls, skip=None, only=None,
                                 name='self.proxy', from_instance=None):
    """Automates delegation of __specials__ for a proxying type."""

    if only:
        dunders = only
    else:
        if skip is None:
            skip = ('__slots__', '__del__', '__getattribute__',
                    '__metaclass__', '__getstate__', '__setstate__')
        dunders = [m for m in dir(from_cls)
                   if (m.startswith('__') and m.endswith('__') and
                       not hasattr(into_cls, m) and m not in skip)]

    for method in dunders:
        try:
            fn = getattr(from_cls, method)
            if not hasattr(fn, '__call__'):
                continue
            fn = getattr(fn, 'im_func', fn)
        except AttributeError:
            continue
        try:
            spec = compat.inspect_getargspec(fn)
            fn_args = inspect.formatargspec(spec[0])
            d_args = inspect.formatargspec(spec[0][1:])
        except TypeError:
            fn_args = '(self, *args, **kw)'
            d_args = '(*args, **kw)'

        py = ("def %(method)s%(fn_args)s: "
              "return %(name)s.%(method)s%(d_args)s" % locals())

        env = from_instance is not None and {name: from_instance} or {}
        compat.exec_(py, env)
        try:
            env[method].__defaults__ = fn.__defaults__
        except AttributeError:
            pass
        setattr(into_cls, method, env[method])