cython

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# mode: run
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from cpython.number cimport PyNumber_InPlacePower
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def ipow(a, b, c):
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    # As far as DW can tell, calling through this C API call is the
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    # only way to actually use ternary __ipow__
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    return PyNumber_InPlacePower(a, b, c)
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# three-arg ipow can only work safely on Py3.8+
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# and so tests are in a separate file
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cdef class TwoOrThreeArgIPow:
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    """
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    >>> a = TwoOrThreeArgIPow('a')
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    >>> a**=2
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    >>> print(a)
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    a**2[None]
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    >>> print(ipow(TwoOrThreeArgIPow('a'), 'x', 'y'))
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    a**x[y]
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    """
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    cdef str name
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    def __init__(self, name):
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        self.name = name
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    def __ipow__(self, other, base=None):
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        return f"{self.name}**{other}[{base}]"
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cdef class ThreeArgIPow:
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    """
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    Note that it's not possible to detect if this is called in a 2-arg context
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    since the Python interpreter just passes None
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    >>> a = ThreeArgIPow('a')
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    >>> a**=2
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    >>> print(a)
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    a**2[None]
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    >>> print(ipow(ThreeArgIPow('a'), 'x', 'y'))
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    a**x[y]
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    """
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    cdef str name
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    def __init__(self, name):
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        self.name = name
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    def __ipow__(self, other, base):
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        return f"{self.name}**{other}[{base}]"
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