Writing an immutable object in python

[Diez B. Roggisch]

> The change in the poision occurs becouse int() is an immutable object.
> 
> if I will do the same with a user-defined object, This reference
> manipulating will not happen. So, every entry in the array will refer
> to the same instance.
> 
> Is there a way to bypass it (or perhaps to write a self-defined
> immutable object)?

This has nothing to do with int being mutable or not. It only has to do 
with _list_ being mutable, and of course teh semantics of the

_ * _ : list x int -> list

operator, which simply shallow copies the list. So assigning to some

l[i]


will replace that entry - regardless of what is stored there. And that 
is all you do. The mutablity of an object only comes into place if you 
try and do

l[i].some_mutating_op()

That catches many people by surprise - but you don't do such a thing :)

And besides: making an object immutable would mean that the only way to 
create an instance would be the constructor - rendering the purpose of 
the whole exercise somewhat moot - as then you'd have to call the 
constructor individually for each index you want to alter anyway. Which 
you have to do in the case of mutable objects, too. So - no gain there.

Regards,

Diez