New submission from Serhiy Storchaka:
For now using formatted string literals (PEP498) is the fastest way of
formatting strings.
$ ./python -m perf timeit -s 'k = "foo"; v = "bar"' -- '"{!s} = {!r}".format(k,
v)'
Median +- std dev: 3.96 us +- 0.17 us
$ ./python -m perf timeit -s 'k = "foo"; v = "bar"' -- 'f"{k!s} = {v!r}"'
Median +- std dev: 1.09 us +- 0.08 us
The compiler could translate new-style formatting with literal format string to
the equivalent formatted string literal. The code '{!s} = {!r}'.format(k, v)
could be translated to
t1 = k; t2 = v; f'{t1!r} = {t2!s}'; del t1, t2
or even simpler if k and v are initialized local variables.
$ ./python -m perf timeit -s 'k = "foo"; v = "bar"' -- 't1 = k; t2 = v;
f"{t1!s} = {t2!r}"; del t1, t2'
Median +- std dev: 1.22 us +- 0.05 us
This is not easy issue and needs first implementing the AST optimizer.
----------
components: Interpreter Core
messages: 277689
nosy: eric.smith, serhiy.storchaka
priority: low
severity: normal
status: open
title: Accelerate 'string'.format(value, ...) by using formatted string literals
type: performance
versions: Python 3.7
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue28308>
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