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

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how numpy can handle operations, when numpy.array on right side?

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

i thought list should try add array (with list.__add__ method) , fail.

additional example @m4rtini's answer: __radd__ called when __add__ fails , objects of different types:

class a():     def __radd__(self, other):         return "result" print(a()+a()) #fail typeerror 

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 >>result of >>__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 called implement binary arithmetic operations (+, -, *, /, %, divmod(), pow(), **, <<, >>, &, ^, |) reflected (swapped) operands. these functions called if left operand not support corresponding operation , operands of different types. [2]


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