1 # interfaceutil.py - Utilities for declaring interfaces.

     2 #

     3 # Copyright 2018 Gregory Szorc <gregory.szorc@gmail.com>

     4 #

     5 # This software may be used and distributed according to the terms of the

     6 # GNU General Public License version 2 or any later version.

     7 

     8 # zope.interface imposes a run-time cost due to module import overhead and

     9 # bookkeeping for declaring interfaces. So, we use stubs for various

    10 # zope.interface primitives unless instructed otherwise.

    11 

    12 from __future__ import absolute_import

    13 

    14 from .. import (

    15     encoding,

    16 )

    17 

    18 if encoding.environ.get('HGREALINTERFACES'):

    19     from ..thirdparty.zope import (

    20         interface as zi,

    21     )

    22 

    23     Attribute = zi.Attribute

    24     Interface = zi.Interface

    25     implementer = zi.implementer

    26 else:

    27     class Attribute(object):

    28         def __init__(self, __name__, __doc__=''):

    29             pass

    30 

    31     class Interface(object):

    32         def __init__(self, name, bases=(), attrs=None, __doc__=None,

    33                  __module__=None):

    34             pass

    35 

    36     def implementer(*ifaces):

    37         def wrapper(cls):

    38             return cls

    39 

    40         return wrapper