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Juneau Lim13,362 Points
Am I understanding subclassing correctly?
I have read this question. I think my understanding is right, but I am not 100% sure.
So, if there was no
__init__ method in the subclass, it means that there was no constructor, so even if we declare an object of that class, it calls its superclass, and the actual class becomes its superclass.
The class with only
__new__ method only provide functionality(whether with the extra method or only with new itself) but not the class instant.
Is this the case? I have learned OOP with Java, so if there is anything wrong, comparing with Java equivalent will help me understand. Thanks in advance!
Steven Parker215,372 Points
Comparing with other languages might not yield the clearest understanding. In other languages, a "constructor" may combine the functionality that is separated in Python into "
__new__" and "
__init__", but provide less control over the process.
__new__" lets you control what is actually returned as the new "instance", and "
__init__" establishes the starting conditions (but doesn't return anything).
The Python Reference manual (check it for more details) says this about the difference:
__new__()is intended mainly to allow subclasses of immutable types (like int, str, or tuple) to customize instance creation. It is also commonly overridden in custom metaclasses in order to customize class creation.