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Ben Slivinn10,156 Points
Could you please explain why are we using self = str.__new__(*args)?
Object-Oriented Python, Subclassing Built-ins.
I tried to play with ReversedStr's new() method and add a loop to accept multiple arguments (rs = ReversedStr(321, 987), and the first argument successfully converted to string type because of str.new() (In my understanding its because str.new()), but the second one isn't. That is when I understood that I don't really get it why you are using str.new().
class ReverseStr(str): def __new__(*args): self = str.__new__(*args) # self is just a variable name. self = self[::-1] return self rs = ReverseStr(321) print(rs)
Chris FreemanTreehouse Moderator 68,332 Points
__new__ when you need to control the creation of a new instance.
__init__ when you need to control initialization of a new instance.
__new__ is the first step of instance creation. It's called first,
and is responsible for returning a new instance of your class. In
__init__ doesn't return anything; it's only responsible for
initializing the instance after it's been created.
In general, you shouldn't need to override
__new__ unless you're
subclassing an immutable type like str, int, unicode or tuple.
*args is used in the
__new__ signature to allow an arbitrary number of arguments to be passed in. Using
*args again on the call to
str.__new__(*args) passes these arbitrary number of arguments on to the parent's method.
By using the call to
str.__new__ you get all the parent class attributes and methods.
__new__() method creates and returns exactly one object. It can not be used to create multiple objects.
Post back if you need more help. Good luck!!!