As pointed out already, f-strings and format are subtly different (not
counting that one can eval and the other cannot). Besides quoting, the
f-sting mini language has diverged from format's
>>> spam="Spam"
>>> f"{spam=}"
"spam='Spam'"
>>> "{spam=}".format(spam=spam)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
KeyError: 'spam='
I created a package some time ago to do exactly this
https://pypi.org/project/f-yeah/
On Thu, Jun 24, 2021 at 10:07 AM Luciano Ramalho <luci...@ramalho.org>
wrote:
> I don't think that would be a good idea since we already have
> .format() which covers that use case and is more flexible than
> f-strings (it supports positional arguments, as well as *args and
> **kwargs).
>
> I think keeping f-strings simple is a better idea.
>
> Best,
>
> Luciano
>
> On Thu, Jun 24, 2021 at 1:30 PM Eric Nieuwland <eric.nieuwl...@gmail.com>
> wrote:
> >
> > In a recent discussion with a colleague we wondered if it would be
> possible to postpone the evaluation of an f-string so we could use it like
> a regular string and .format() or ‘%’.
> >
> > I found
> https://stackoverflow.com/questions/42497625/how-to-postpone-defer-the-evaluation-of-f-strings
> and tweaked it a bit to:
> >
> > import inspect
> >
> > class DelayedFString(str):
> > def __str__(self):
> > vars = inspect.currentframe().f_back.f_globals.copy()
> > vars.update(inspect.currentframe().f_back.f_locals)
> > return self.format(**vars)
> >
> > delayed_fstring = DelayedFString("The current name is {name}")
> >
> > # use it inside a function to demonstrate it gets the scoping right
> > def new_scope():
> > names = ["foo", "bar"]
> > for name in names:
> > print(delayed_fstring)
> >
> > new_scope()
> >
> >
> > While this does what it should it is very slow.
> > So I wondered whether it would be an idea to introduce d-strings
> (delayed f-strings) and make f-strings syntactic sugar for
> >
> > f"The current name is {name}" = str(d"The current name is {name}")
> >
> >
> > And perhaps access to the variables and conversions specified in the
> d-string.
> >
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>
>
>
> --
> Luciano Ramalho
> | Author of Fluent Python (O'Reilly, 2015)
> | http://shop.oreilly.com/product/0636920032519.do
> | Technical Principal at ThoughtWorks
> | Twitter: @ramalhoorg
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