If I am creating my own class in Python, what function should I define so as to allow the use of the ‘in’ operator, e.g.
class MyClass(object): ... m = MyClass() if 54 in m: ...
A more complete answer is:
class MyClass(object): def __init__(self): self.numbers = [1,2,3,4,54] def __contains__(self, key): return key in self.numbers
Here you would get True when asking if 54 was in m:
>>> m = MyClass() >>> 54 in m True
You might also want to take a look at an infix operator override framework I was able to use to create a domain-specific language: