[Python-Dev] PEP-498: Literal String Formatting

[Alexander Walters]

Please do not change the meaning of the vestigial U''.  It was re-added 
to the language to fix a problem, rebinding it to another meaning 
introduces new problems.  We have plenty of other letters in the 
alphabet to use.

On 8/8/2015 05:34, Nick Coghlan wrote:
> On 8 August 2015 at 11:39, Eric V. Smith <eric at trueblade.com> wrote:
>> Following a long discussion on python-ideas, I've posted my draft of
>> PEP-498. It describes the "f-string" approach that was the subject of
>> the "Briefer string format" thread. I'm open to a better title than
>> "Literal String Formatting".
> Thanks you for your work on this - it's a very cool concept!
>
> I've also now written and posted an initial draft of PEP 500, based
> directly on PEP 498, which formalises the "__interpolate__" builtin
> idea I raised in those threads, along with a PEP 292 based syntax
> proposal that aims to be as simple as possible for the simple case of
> interpolating existing variables, while still allowing the use of
> braces to permit embedding of arbitrary expressions and formatting
> directives.
>
> it turned out this approach provided an unanticipated benefit that I
> only discovered while writing the PEP: by defining a separate
> "__interpolateb__" builtin, it's straightforward to define binary
> interpolation in terms of bytes.__mod__, while still defining text
> interpolation in terms of str.format.
>
> The previously-redundant-in-python-3 'u' prefix also finds new life as
> a way of always requesting the default string interpolation, even if
> __interpolate__ has been overridden in the current namespace to mean
> something else (like il8n string translation).
>
> Cheers,
> Nick.
>