flaming vs accuracy [was Re: Performance of int/long in Python 3]

[Terry Reedy]

On 3/28/2013 10:38 AM, Chris Angelico wrote:

> PEP393 strings have two optimizations, or kinda three:
>
> 1a) ASCII-only strings
> 1b) Latin1-only strings
> 2) BMP-only strings
> 3) Everything else
>
> Options 1a and 1b are almost identical - I'm not sure what the detail
> is, but there's something flagging those strings that fit inside seven
> bits. (Something to do with optimizing encodings later?)

Yes. 'Encoding' an ascii-only string to any ascii-compatible encoding 
amounts to a simple copy of the internal bytes. I do not know if *all* 
the codecs for such encodings are 393-aware, but I do know that the 
utf-8 and latin-1 group are. This is one operation that 3.3+ does much 
faster than 3.2-


-- 
Terry Jan Reedy