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[Python-Dev] Should PEP 498 specify if rf'...' is valid?

Nick Coghlan ncoghlan at gmail.com
Fri Oct 23 11:20:45 EDT 2015 
On 22 October 2015 at 19:12, Eric V. Smith <eric at trueblade.com> wrote:
> On 10/22/2015 1:09 PM, Ryan Gonzalez wrote:
>> But it'd be weird now if fR worked but fbR didn't.
>
> Or bR (which is currently allowed) but not fbR in the future.

My own objection isn't to allowing "fR" or "fbR", it's to allowing the
uppercase "F".

I also don't understand why we can't say "if 'f' is part of a string
prefix, it must be first".

That would mean we kept the current 14 combinations:

    ['B', 'BR', 'Br', 'R', 'RB', 'Rb', 'U', 'b', 'bR', 'br', 'r',
'rB', 'rb', 'u']

And added only 13 more possibilities, being a lowercase 'f' prefix on
its own, and as a prefix for the various b/r combinations:

    ['fB', 'fBR', 'fBr', 'fR', 'fRB', 'fRb', 'fb', 'fbR', 'fbr', 'fr',
'frB', 'frb']

I don't think it would ever be worth the compatibility break to
require lowercase for 'rbu', or to enforce a particular relative order
(although those could be good pylint rules, if they aren't already),
but there's no such restrictions for the new 'f' prefix.

Regards,
Nick.

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