[Python-ideas] Draft2 PEP on string interpolation

[Mike Miller]

With the major design decisions made, behold version 2 of my draft PEP on string 
interpolation.

It's now significantly shorter due to removal of most of the i18n related 
discussion, pruning, as well as simplification of the prose itself.  I don't 
expect many changes from here on:

     https://bitbucket.org/mixmastamyk/docs/src/default/pep/pep-05XX.rst

TL;DR:  Here is a summary table and comparisons with my current understanding of 
the other proposals, please correct if they are now out of date:


String Interpolation PEP Comparison
===================================


=================   =================   =================   =================
PEP                 PEP 498             PEP 501             Draft PEP
=================   =================   =================   =================
Name                Format/f-string     Gen. Purpose Str…   Expression-string
Prefix              f''                 i''                 e''
Syntax              str.format()+       .format+Template+   str.format()+
Returns             String join expr…   Object              Object
Immediate Render    Yes                 No                  Yes
Deferred Render     No                  Yes, str, mutable   Yes
I18n Support        No                  Yes                 Input available
Escaping Hook       No                  No                  Yes, manual
=================   =================   =================   =================

The table can be found here and updated via pull-request:

      https://bitbucket.org/mixmastamyk/docs/src/default/pep/pep_comparison.rst

-Mike