29 lines
1.4 KiB
Python
29 lines
1.4 KiB
Python
"""Code pulled from future python versions, here for compatibility"""
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def total_ordering(cls):
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"""Class decorator that fills in missing ordering methods"""
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convert = {
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'__lt__': [('__gt__', lambda self, other: other < self),
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('__le__', lambda self, other: not other < self),
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('__ge__', lambda self, other: not self < other)],
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'__le__': [('__ge__', lambda self, other: other <= self),
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('__lt__', lambda self, other: not other <= self),
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('__gt__', lambda self, other: not self <= other)],
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'__gt__': [('__lt__', lambda self, other: other > self),
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('__ge__', lambda self, other: not other > self),
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('__le__', lambda self, other: not self > other)],
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'__ge__': [('__le__', lambda self, other: other >= self),
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('__gt__', lambda self, other: not other >= self),
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('__lt__', lambda self, other: not self >= other)]
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}
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roots = set(dir(cls)) & set(convert)
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if not roots:
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raise ValueError('must define at least one ordering operation: < > <= >=')
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root = max(roots) # prefer __lt__ to __le__ to __gt__ to __ge__
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for opname, opfunc in convert[root]:
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if opname not in roots:
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opfunc.__name__ = opname
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opfunc.__doc__ = getattr(int, opname).__doc__
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setattr(cls, opname, opfunc)
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return cls
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