[Python-Dev] Inplace operations for PyLong objects

[Joe Jevnik]

The string concat optimization happens in the interpreter dispatch for
INPLACE_ADD

On Fri, Sep 1, 2017 at 9:10 PM, Greg Ewing <greg.ewing at canterbury.ac.nz>
wrote:

> Chris Angelico wrote:
>
>> This particular example is safe, because the arguments get passed
>> individually - so 'args' has one reference, plus there's one more for
>> the actual function call
>>
>
> However, that's also true when you use the += operator,
> so if the optimisation is to trigger at all in any useful
> case, the refcount threshold needs to be set higher than
> 1.
>
> Some experiments I did suggest that if you set it high
> enough for x += y to trigger it, then it will also be
> triggered in Joe's case.
>
> BTW, isn't there already a similar optimisation somewhere
> for concatenating strings? Does it still exist? How does
> it avoid this issue?
>
> --
> Greg
>
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