expr.py 文件源码

def is_number(self):
        """Returns True if 'self' has no free symbols.
        It will be faster than `if not self.free_symbols`, however, since
        `is_number` will fail as soon as it hits a free symbol.

        Examples
        ========

        >>> from sympy import log, Integral
        >>> from sympy.abc import x

        >>> x.is_number
        False
        >>> (2*x).is_number
        False
        >>> (2 + log(2)).is_number
        True
        >>> (2 + Integral(2, x)).is_number
        False
        >>> (2 + Integral(2, (x, 1, 2))).is_number
        True

        """
        return all(obj.is_number for obj in self.args)