[Python-ideas] Briefer string format

[Nick Coghlan]

On 7 August 2015 at 06:35, Wes Turner <wes.turner at gmail.com> wrote:
>
> On Aug 6, 2015 3:03 PM, "Guido van Rossum" <guido at python.org> wrote:
>>
>> Unfortunately, all spellings that require calling locals() are wrong.
>
> Is this where the potential source of surprising error is?

Yes - it's what creates the temptation for people to use
sys._getframe() to hide the locals() calls, and either approach hides
the name references from lexical analysers (hence Barry's comment
about false alarms regarding "unused locals" when scanning code that
uses flufl.il8n). When people are being tempted to write code that is
too clever for a computer to easily follow without executing it,
that's cause for concern (being able to *write* such code is useful
for exploratory purposes, but it's also the kind of thing that's
desirable to factor out as a code base matures).

When it comes to name based string interpolation, the current
"correct" approach (which even computers can read) requires
duplicating the name references explicitly in constructs like:

    print("This interpolates {a} and {b}".format(a=a, b=b))

Which doesn't fare well for readability when compared to
sys._getframe() based implicit approaches like flufl.il8n's:

    print(_("This interpolates $a and $b"))

The f-string proposal provides a way to write the latter kind of
construct in a more explicit way that even computers can learn to read
(without executing it).

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia