[Python-Dev] Subtle difference between f-strings and str.format()
Serhiy Storchaka
storchaka at gmail.com
Fri Mar 30 06:05:59 EDT 2018
30.03.18 02:16, Steven D'Aprano пише:
> Is there a down-side to 2b? It sounds like something you might end up
> doing at a later date regardless of what you do now.
This complicate the compiler and the eval loop, especially in the case
of nested substitutions in formats, like
f'{value:+{width:d}.{prec:d}f}'
The speed gain can be too small. The complex implementation of the
opcode should be tightly integrated with the ceval loop, otherwise we
can get a slow down, as in one of my experimental implementation of
BUILD_STRING (https://bugs.python.org/issue27078#msg270505).
The exact benefit is unknown until this feature be implemented.
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