Immutability and Python

[Jean-Michel Pichavant]

----- Original Message -----
> 2012/10/29 Jean-Michel Pichavant <jeanmichel at sequans.com>:
> >
> > "return NumWrapper(self.number + 1) "
> >
> > still returns a(nother) mutable object.
> >
> > So what's the point of all this ?
> >
> > JM
> >
> 
> Well sure but it doesn't modify the first object, just creates a new
> one.  There are in general good reasons to do that, for example I can
> then compose things nicely:
> 
> num.increment().increment()
> 
> or I can parallelize operations safely not caring about the order of
> operations.
> 
> But while I do this all the time with more functional languages, I
> don't tend to do exactly the same in Python, because I have the
> impression that is not worth, but maybe I'm wrong..
> 

In an OOP language num.increment() is expected to modify the object in place.
So I think you're right when you say that functional languages technics do not necessarily apply to Python, because they don't.

I would add that what you're trying to suggest in the first post was not really about immutability, immutable objects in python are ... well immutable, they can be used as a dict key for instance, your NumWrapper object cannot.


JM



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