Function _setattr_cm

lib/matplotlib/cbook.py:2136–2176

Temporarily set some attributes; restore original state at context exit.

(obj, **kwargs)

@contextlib.contextmanager
def _setattr_cm(obj, **kwargs):
    """
    Temporarily set some attributes; restore original state at context exit.
    """
    sentinel = object()
    origs = {}
    for attr in kwargs:
        orig = getattr(obj, attr, sentinel)
        if attr in obj.__dict__ or orig is sentinel:
            # if we are pulling from the instance dict or the object
            # does not have this attribute we can trust the above
            origs[attr] = orig
        else:
            # if the attribute is not in the instance dict it must be
            # from the class level
            cls_orig = getattr(type(obj), attr)
            # if we are dealing with a property (but not a general descriptor)
            # we want to set the original value back.
            if isinstance(cls_orig, property):
                origs[attr] = orig
            # otherwise this is _something_ we are going to shadow at
            # the instance dict level from higher up in the MRO.  We
            # are going to assume we can delattr(obj, attr) to clean
            # up after ourselves.  It is possible that this code will
            # fail if used with a non-property custom descriptor which
            # implements __set__ (and __delete__ does not act like a
            # stack).  However, this is an internal tool and we do not
            # currently have any custom descriptors.
            else:
                origs[attr] = sentinel

    try:
        for attr, val in kwargs.items():
            setattr(obj, attr, val)
        yield
    finally:
        for attr, orig in origs.items():
            if orig is sentinel:
                delattr(obj, attr)
            else:
                setattr(obj, attr, orig)


class _OrderedSet(collections.abc.MutableSet):