66 lines
2.2 KiB
Python
66 lines
2.2 KiB
Python
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# The MIT License (MIT)
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# Copyright (c) 2010 Benjamin Peterson <benjamin@python.org>
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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# The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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# DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
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# OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
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# OR OTHER DEALINGS IN THE SOFTWARE.
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"""Finalization with weakrefs
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This is designed for avoiding __del__.
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"""
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from __future__ import print_function
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import sys
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import traceback
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import weakref
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__author__ = "Benjamin Peterson <benjamin@python.org>"
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class OwnerRef(weakref.ref):
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"""A simple weakref.ref subclass, so attributes can be added."""
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pass
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def _run_finalizer(ref):
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"""Internal weakref callback to run finalizers"""
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del _finalize_refs[id(ref)]
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finalizer = ref.finalizer
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item = ref.item
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try:
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finalizer(item)
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except Exception: # pragma: no cover
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print("Exception running {}:".format(finalizer), file=sys.stderr)
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traceback.print_exc()
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_finalize_refs = {}
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def track_for_finalization(owner, item, finalizer):
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"""Register an object for finalization.
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``owner`` is the the object which is responsible for ``item``.
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``finalizer`` will be called with ``item`` as its only argument when
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``owner`` is destroyed by the garbage collector.
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"""
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ref = OwnerRef(owner, _run_finalizer)
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ref.item = item
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ref.finalizer = finalizer
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_finalize_refs[id(ref)] = ref
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