mercurial/utils/interfaceutil.py

packaging: blindly factor out trap's cleanup function in builddeb

This commit blindly extracts builddeb's trap routine in a dedicated function.
While doing so, I think two bugs are exposed, which will be addressed in the
next commits:

- single quoting around '$CLEANUP' will always evaluate to the literal
  '$CLEANUP' regardless of the variable's value. The "if" will always be true.
- the removal operation will not expand $PWD (and a variable expansion would
  need double quotes, anyways.

# interfaceutil.py - Utilities for declaring interfaces.
#
# Copyright 2018 Gregory Szorc <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

# zope.interface imposes a run-time cost due to module import overhead and
# bookkeeping for declaring interfaces. So, we use stubs for various
# zope.interface primitives unless instructed otherwise.

from __future__ import absolute_import

from .. import (
    encoding,
)

if encoding.environ.get('HGREALINTERFACES'):
    from ..thirdparty.zope import (
        interface as zi,
    )

    Attribute = zi.Attribute
    Interface = zi.Interface
    implementer = zi.implementer
else:
    class Attribute(object):
        def __init__(self, __name__, __doc__=''):
            pass

    class Interface(object):
        def __init__(self, name, bases=(), attrs=None, __doc__=None,
                 __module__=None):
            pass

    def implementer(*ifaces):
        def wrapper(cls):
            return cls

        return wrapper