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git-subtree-dir: SpiffWorkflow git-subtree-split: 63db3e45947ec66b8d0efc2c74064004f8ff482c
133 lines
3.8 KiB
Python
133 lines
3.8 KiB
Python
# -*- coding: utf-8 -*-
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from builtins import object
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#
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# DO NOT EDIT THIS FILE.
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# THIS CODE IS TAKE FROM Exscript.util:
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# https://github.com/knipknap/exscript/tree/master/src/Exscript/util
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#
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# Copyright (C) 2007-2010 Samuel Abels.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License version 2, as
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# published by the Free Software Foundation.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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"""
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Weak references to bound and unbound methods.
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"""
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import weakref
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class DeadMethodCalled(Exception):
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"""
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Raised by :class:`WeakMethod` if it is called when the referenced object
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is already dead.
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"""
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pass
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class WeakMethod(object):
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"""
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Do not create this class directly; use :class:`ref()` instead.
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"""
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__slots__ = 'name', 'callback'
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def __init__(self, name, callback):
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"""
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Constructor. Do not use directly, use :class:`ref()` instead.
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"""
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self.name = name
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self.callback = callback
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def _dead(self, ref):
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if self.callback is not None:
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self.callback(self)
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def get_function(self):
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"""
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Returns the referenced method/function if it is still alive.
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Returns None otherwise.
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:rtype: callable|None
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:returns: The referenced function if it is still alive.
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"""
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raise NotImplementedError()
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def isalive(self):
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"""
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Returns True if the referenced function is still alive, False
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otherwise.
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:rtype: bool
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:returns: Whether the referenced function is still alive.
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"""
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return self.get_function() is not None
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def __call__(self, *args, **kwargs):
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"""
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Proxied to the underlying function or method. Raises
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:class:`DeadMethodCalled` if the referenced function is dead.
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:rtype: object :returns: Whatever the referenced function returned.
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"""
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method = self.get_function()
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if method is None:
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raise DeadMethodCalled('method called on dead object ' + self.name)
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method(*args, **kwargs)
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class _WeakMethodBound(WeakMethod):
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__slots__ = 'name', 'callback', 'f', 'c'
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def __init__(self, f, callback):
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name = f.__self__.__class__.__name__ + '.' + f.__func__.__name__
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WeakMethod.__init__(self, name, callback)
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self.f = f.__func__
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self.c = weakref.ref(f.__self__, self._dead)
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def get_function(self):
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cls = self.c()
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if cls is None:
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return None
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return getattr(cls, self.f.__name__)
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class _WeakMethodFree(WeakMethod):
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__slots__ = 'name', 'callback', 'f'
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def __init__(self, f, callback):
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WeakMethod.__init__(self, f.__class__.__name__, callback)
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self.f = weakref.ref(f, self._dead)
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def get_function(self):
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return self.f()
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def ref(function, callback=None):
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"""
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Returns a weak reference to the given method or function.
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If the callback argument is not None, it is called as soon
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as the referenced function is garbage deleted.
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:type function: callable
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:param function: The function to reference.
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:type callback: callable
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:param callback: Called when the function dies.
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"""
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try:
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function.__func__
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except AttributeError:
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return _WeakMethodFree(function, callback)
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return _WeakMethodBound(function, callback)
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