python捕获函数

我写了下面的代码.

from operator import mul
from operator import truediv #python 3.2

class Vec(list):

    def __mul__(self, other):
        return Vec(map(mul, self, other))

    def __truediv__(self, other):
        return Vec(map(truediv, self, other))


>>> xs = Vec([1,2,3,4,5])
>>> ys = Vec([4,5,6,7,4])
>>> zs = xs * ys
>>> zs.__class__
<class 'vector.Vec'>
>>> zs
[4, 10, 18, 28, 20]

但是有可能创建这样的东西：

class Vec(list):

    allowed_math = [__add__, __mul__, __truediv__, __subtract__] # etc

    def __catchfunction__(self, other, function):
        if function in allowed_math:
            return Vec(map(function, self, other))

为了清楚起见,这并不是关于我尝试重新创建NumPy的问题,我只是想了解一个人如何使用Python.

解决方法:

实现预期效果的一种方法是：

class Vec(list):
    pass

functions = {"__add__": operator.add,
             "__mul__": operator.mul,
             "__truediv__": operator.truediv,
             "__sub__": operator.sub}
for name, op in functions.iteritems():
    setattr(Vec, name, lambda self, other, op=op: Vec(map(op, self, other)))

请注意,必须使用op = op参数,以避免lambda函数成为op的闭包.

但是,使用NumPy可能会好得多–与使用纯Python创建自己的代码相比,它提供了更加通用和有效的数值数组实现.

标签：operator-keyword,python,function
来源： https://codeday.me/bug/20191201/2078587.html