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I would like to make bool binary operations using the magic methods for these operators. For example, I can get a < b as getattr(a, '__lt__')(b) or a == b as getattr(a, '__eq__')(b).
Can I get a in b and a is b in such a way?
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Magic methods are special methods in python that have double underscores (dunder) on both sides of the method name. Magic methods are predominantly used for operator overloading.
Let's take a closer look at these 3 magic methods: __new__(cls, [...) __new__ is the first method to get called in an object's instantiation. It takes the class, then any other arguments that it will pass along to __init__ .
To use the greater than operator on custom objects, define the __gt__() “dunder” magic method that takes two arguments: self and other . You can then use attributes of the custom objects to determine if one is greater than the other.
For in, the correct dunder method is __contains__.
There is no method for is, because this is equivalent to id(a) == id(b). It compares the actual object ID used under the hood by Python, so is used to compare object identity, not object contents. Overwriting it within a class would break Python's object model, so it is not allowed.
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in is __contains__ and is does not have a dunder method. I strongly suggest you use the functions in the operator module:
a < b => operator.lt(a, b)
a == b => operator.eq(a, b)
a in b => operator.contains(a, b)
a is b => operator.is_(a, b)
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