处理右侧对象的操作（__r * __方法）

Question

当numpy位于右侧时，numpy.array如何处理操作？

>>> [1,2,3]+numpy.array([1,2,3])
array([2, 4, 6])

我认为list应该尝试将array（使用list.__add__方法）添加到自身并失败。

@ M4rtini答案的附加示例：__radd__失败且对象属于不同类型时调用__add__：

class A():
    def __radd__(self, other):
        return "result"
print(A()+A()) #fail with TypeError

Answer 1

class A(object):
    def __radd__(self, other):
        print ("__radd__ called of A")
        return "result of A"

class B(object):
    def __radd__(self, other):
        print ("__radd__ called of B")
        return "result of B"


print (B()+A())
print (A()+B())

>>__radd__ called of A
>>result of A
>>__radd__ called of B
>>result of B

Documentation

object.__radd__(self, other)
object.__rsub__(self, other)
object.__rmul__(self, other)
object.__rdiv__(self, other)
object.__rtruediv__(self, other)
object.__rfloordiv__(self, other)
object.__rmod__(self, other)
object.__rdivmod__(self, other)
object.__rpow__(self, other)
object.__rlshift__(self, other)
object.__rrshift__(self, other)
object.__rand__(self, other)
object.__rxor__(self, other)
object.__ror__(self, other)

     

调用这些方法来实现二进制算术运算   （+， - ，*，/，％，divmod（），pow（），**，＆lt;＆lt;，＆gt;＆gt;，＆amp;，^，|）反映   （交换）操作数。 仅在左侧调用这些函数   操作数不支持相应的操作和操作数   属于不同类型。 [2]