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# -*- coding: utf-8 -*-
#
# AWL simulator - Instance write protection
#
# Copyright 2015 Michael Buesch <m@bues.ch>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
from __future__ import division, absolute_import, print_function, unicode_literals
#from awlsim.common.cython_support cimport * #@cy
from awlsim.common.compat import *
__all__ = [
"OptionalImmutable",
]
__useDummy = False
if isMicroPython: #@nocov
__useDummy = True
if __useDummy: #@nocov
class OptionalImmutable(object):
"""Optional instance write protection.
Dummy implementation.
"""
_immutable = False
def isImmutable(self):
return self._immutable
def setImmutable(self):
self._immutable = True
else:
class OptionalImmutable(object):
"""Optional instance write protection.
By default, instances are not write protected (not immutable).
If setImmutable() is called, assignment to instance attributes
and deletion of attributes is restricted.
This cannot be reverted.
Subclass this class to use this mechanism."""
__slots__ = (
"_immutable",
)
def __new__(cls, *args, **kwargs):
self = super(OptionalImmutable, cls).__new__(cls)
super(OptionalImmutable, self).__setattr__("_immutable", False)
return self
def isImmutable(self):
"""Returns True, if self is immutable."""
return self._immutable
def setImmutable(self):
"""Make self immutable. This is not reversible."""
self._immutable = True
def __setattr__(self, name, value):
if self._immutable: #@nocov
raise AttributeError("Assignment to '%s' "
"of immutable %s." %\
(name, str(type(self))))
super(OptionalImmutable, self).__setattr__(name, value)
def __delattr__(self, name):
if self._immutable: #@nocov
raise AttributeError("Deletion of '%s' "
"from immutable %s." %\
(name, str(type(self))))
super(OptionalImmutable, self).__delattr__(name)
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