basic.py 文件源码

def __eq__(self, other):
        """Return a boolean indicating whether a == b on the basis of
        their symbolic trees.

        This is the same as a.compare(b) == 0 but faster.

        Notes
        =====

        If a class that overrides __eq__() needs to retain the
        implementation of __hash__() from a parent class, the
        interpreter must be told this explicitly by setting __hash__ =
        <ParentClass>.__hash__. Otherwise the inheritance of __hash__()
        will be blocked, just as if __hash__ had been explicitly set to
        None.

        References
        ==========

        from http://docs.python.org/dev/reference/datamodel.html#object.__hash__
        """
        from sympy import Pow
        if self is other:
            return True

        from .function import AppliedUndef, UndefinedFunction as UndefFunc

        if isinstance(self, UndefFunc) and isinstance(other, UndefFunc):
            if self.class_key() == other.class_key():
                return True
            else:
                return False
        if type(self) is not type(other):
            # issue 6100 a**1.0 == a like a**2.0 == a**2
            if isinstance(self, Pow) and self.exp == 1:
                return self.base == other
            if isinstance(other, Pow) and other.exp == 1:
                return self == other.base
            try:
                other = _sympify(other)
            except SympifyError:
                return False    # sympy != other

            if isinstance(self, AppliedUndef) and isinstance(other,
                                                             AppliedUndef):
                if self.class_key() != other.class_key():
                    return False
            elif type(self) is not type(other):
                return False

        return self._hashable_content() == other._hashable_content()