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Özgür Yildirim
4,088 Pointshow to call dunder methods?
Is there a relationship between dunder methods and the function call? For instance,
class Something:
def __amethod__(self):
pass
x = Something()
amethod(x)
I tried this, it does not work. But when I see functions like int(something) or float(something), I think we can do this because they are the so called magic functions. Normally we have to call a method objectofsometype.oneofitsmethods(anargument)
But every now an then there is a method that works like aspecialmethod(aspecialtypeofobjectthatworkswiththemethod, someoptionalargument)
[MOD: added ```python formatting -cf]
2 Answers
Chris Freeman
Treehouse Moderator 68,441 PointsHey Özgür Yildirim, good question.
The Special methods or Dunder methods are not intended to be called directly. It is also not recommended that a user define their own dunder methods.
Each existent dunder method has been defined to handle a class’s behavior under various contexts. Some of these contexts, as you mentioned, are invoked directly by the user.
For example, int(some_object) says call the some_object.__int__() method so the some_object’s class can respond how it wishes to behave in an integer context. This would be is usually to return an integer value, but it may be to raise a TypeError saying “I can not be used in an integer context!”
One exception to calling a dunder method would be though the use of a super() call. This is when you wish to alter the behavior of an inherented dunder method from a parent class.
I’m curious as to the reason you would like to call a dunder method.
Post back if you need more help. Good luck!!!
Özgür Yildirim
4,088 PointsThanks Chris, it got more clear now. I was only confused by the concepts of dunder methods, magic methods, and built-in functions. Because we can use certain functions with objects or variables without having ever defined anything. For a brief time I led myself to believe that I can create the same type of functions if I just dunder it. Now I understand that they are limited in number and correspond to certain operations, such as len() bool() int() float() str() print() == != > >= < >= + += * *= / /= - -= is and in.