Mutable numbers

[Steve Holden]

fraca7 wrote:
> Suresh Jeevanandam a écrit :
> 
>># I am new to python.
>>
>>In python all numbers are immutable. This means there is one object ( a 
>>region in the memory ) created every time we do an numeric operation. I 
>>hope there should have been some good reasons why it was designed this way.
> 
> 
> The memory allocation for integers is optimized. 'Small' integers 
> (between -5 and 100 IIRC) are allocated once and reused. The memory for 
> larger integers is allocated once and reused whenever possible, so the 
> malloc() overhead is negligible.

The first bit's right, the second bit isn't:

  >>> id(12100)
4604168
  >>> id(121*100)
4604204
  >>>

regards
  Steve
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