通过右侧的对象处理操作（r* 方法）

Question

当numpy.array在右侧时，numpy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）添加到自身并且失败 .

@M4rtini 回答的附加示例：__radd__ 在 __add__ 失败且对象类型不同时调用：

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)
These methods are called to implement the binary arithmetic operations (+, -, *, /, %, divmod(), pow(), **, <<, >>, &, ^, |) with reflected (swapped) operands. These functions are only called if the left operand does not support the corresponding operation and the operands are of different types. [2]

通过右侧的对象处理操作（r* 方法）

Handle operation by object on right side (r* methods)

python

operator-overloading

operators

通过右侧的对象处理操作（__r*__ 方法）

Handle operation by object on right side (__r*__ methods)

python

operator-overloading

operators

通过右侧的对象处理操作（r* 方法）

Handle operation by object on right side (r* methods)