why is "self" used in OO-Python?

ssecorp circularfunc at gmail.com
Sat Jul 12 18:32:12 CEST 2008


I first learned about OO from Java.

I much prefer to program in Python though.

However I am consufed about 2 things.

1. Why do I have to pass self into every method in a class? Since I am
always doing why cant this be automated or abstracted away?
Are the instances where I won't pass self?
I imagine there is some tradeoff involved otherwise it would have been
done away with.

2. self.item instead of getters and setters. I thought one of the main
purposes of OO was encapsulation. Doesn't messing with internal object-
representations break this?
I see how the getters and setters could be just visual clutter and you
have to add them to every class so it is annoying a bit in the same
way as self described above.
However I feel like I want getters and setters when I write classes,
not sure of the advantages/disadvantages though.
Only looking at the documentation of a Python-class, will internal
representations be provided?

If I have a class:

class Stack(object):
    def __init__(self, *items):
        self.stack = list(items)

    def append(self, item):
        self.stack.append(item)

    def pop(self):
        return self.stack.pop()

I can get to see the stack with var.stack but then why even implement
append when I could do self.stack.append(x) etc.
That way you could do away with OO completely. So why let people
access the main attribute but not let them manipulate it?
Makes more sense to draw the line to not access any attributes at all
no?



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