59 lines
2.4 KiB
Python
59 lines
2.4 KiB
Python
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"""
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Backport of PEP 562.
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https://pypi.org/search/?q=pep562
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Licensed under MIT
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Copyright (c) 2018 Isaac Muse <isaacmuse@gmail.com>
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Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
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documentation files (the "Software"), to deal in the Software without restriction, including without limitation
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the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software,
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and to permit persons to whom the Software is 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 all copies or substantial portions
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of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
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TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
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CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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IN THE SOFTWARE.
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"""
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from __future__ import unicode_literals
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import sys
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__all__ = ('Pep562',)
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class Pep562(object):
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"""
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Backport of PEP 562 <https://pypi.org/search/?q=pep562>.
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Wraps the module in a class that exposes the mechanics to override `__dir__` and `__getattr__`.
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The given module will be searched for overrides of `__dir__` and `__getattr__` and use them when needed.
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"""
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def __init__(self, name):
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"""Acquire `__getattr__` and `__dir__`, but only replace module for versions less than Python 3.7."""
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self._module = sys.modules[name]
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self._get_attr = getattr(self._module, '__getattr__', None)
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self._get_dir = getattr(self._module, '__dir__', None)
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sys.modules[name] = self
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def __dir__(self):
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"""Return the overridden `dir` if one was provided, else apply `dir` to the module."""
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return self._get_dir() if self._get_dir else dir(self._module)
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def __getattr__(self, name):
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"""Attempt to retrieve the attribute from the module, and if missing, use the overridden function if present."""
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try:
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return getattr(self._module, name)
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except AttributeError:
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if self._get_attr:
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return self._get_attr(name)
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raise
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