Overloading Bitwise Operators to Work with Booleans in Python

Question

I have a class that I want to be able to do bitwise operations on in some cases.

class Measurement(object):
    def __init__(self, value = None, category = None, measure = None):
        self.value = value
        self.category = category
        self.measure = measure    

    def __nonzero__(self):
        return self.value.__nonzero__()

    def __or__(self, other):
        return self.__nonzero__() | other

a = False
b = Measurement(True)

At this point c = b | a works, but c = a | b gives a type error. How do I get it to work both ways?

Also, is there a more elegant way to do this; for example, I had hoped that by just defining __nonzero__, I might get the right behaviour, but that's not the case.

I'm using Python 2.7.

Aha, this reminds me of a similar question I saw solved. It was about implementing a multiplication operation for a custom Vector class, and the solution was to override __rmul__ (and make it call __mul__ with the arguments switched). I wonder if there's a similar solution for this. — Tagc
– Tagc, Commented Jan 11, 2017 at 18:36
This is the way it's suppose to be done. Explicit is better than implicit and all that... — juanpa.arrivillaga
– juanpa.arrivillaga, Commented Jan 11, 2017 at 18:40

PProteus · Accepted Answer · 2017-01-11 18:37:23Z

2

By also defining __ror__, as shown below, I get the right behaviour. The second part of the question still stands, however. Is there a more elegant way?

def __ror__(self, other):
    return self.__or__(other)

edited Jan 11, 2017 at 18:37

answered Jan 11, 2017 at 18:36

PProteus

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2 Comments

Tagc Over a year ago

__ror__...I knew it.

Patrick Haugh Over a year ago

No there isn't a better way. You could potentially define self.__ror__ = self.__or__, but I think that would just be more confusing

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