Python call __init__() method only one time

Question

Is there any way to call the init() method of a class only one time. Or how can I disable calling of init() when I create an object from a class?

Answer 1

If you want a singleton, where there is only ever one instance of a class then you can create a decorator like the following as gotten from PEP18:

def singleton(cls):
    instances = {}
    def getinstance():
        if cls not in instances:
            instances[cls] = cls()
        return instances[cls]
    return getinstance

@singleton
class MyClass:
    pass

Try it out:

>>> a = MyClass()
>>> b = MyClass()
>>> a == b
True