Is behavior of += intentional for int?

Steven D'Aprano steve at
Wed Sep 2 01:00:06 CEST 2009

On Tue, 01 Sep 2009 07:04:09 -0700, zaur wrote:

> On 1 сен, 03:31, Steven D'Aprano <st... at REMOVE-THIS->
> wrote:
>> On Mon, 31 Aug 2009 10:21:22 -0700, zaur wrote:
>> > As a result of this debate is not whether we should conclude that
>> > there should be two types of integers in python: 1) immutable
>> > numbers, which behave as constant value; 2) mutable numbers, which
>> > behave as variable value?
>> What can you do with mutable numbers that you can't do with immutable
>> ones, and why do you want to do it?
>> --
>> Steven
> Mutable numbers acts as variable quantity. 

So do immutable numbers bound to a name.

> So when augmented assignment
> is used there is no need to create a new number object in every binary
> operation.

"No need", sure, but there's no *need* to use object oriented code in the 
first place, or garbage collectors, or high level languages, or even 
functions. People got by with GOTO and assembly for years :) We use all 
these things because they make *programming* easier, even if it adds 
runtime overhead.

I'm asking what *problem* you are trying to solve with mutable numbers, 
where immutable numbers are not satisfactory. The only answer I can 
imagine is that you're worried about the overhead of creating new integer 
objects instead of just flipping a few bits in an existing integer 


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