[Python-Dev] [Python-checkins] peps: PEP 460: add .format_map()

[Nick Coghlan]

On 10 January 2014 07:41, Eric V. Smith <eric at trueblade.com> wrote:
> I'm not sure how format_map helps in porting from 2 to 3, since it
> doesn't exist in any version of 2.
>
> Although that said, it's no doubt a useful feature, just not useful in
> code that supports both 2 and 3 with a single code base or when porting
> to 3.

It's purely a matter of consistency with str - if we're adding binary
interpolation back to Python 3 (which I have been persuaded is a good
idea), then we should provide the same three typical spellings of the
operation that str provides.

Cheers,
Nick.

>
> Eric.
>
> On 1/9/2014 4:02 PM, antoine.pitrou wrote:
>> http://hg.python.org/peps/rev/8947cdc6b22e
>> changeset:   5341:8947cdc6b22e
>> user:        Antoine Pitrou <solipsis at pitrou.net>
>> date:        Thu Jan 09 22:02:01 2014 +0100
>> summary:
>>   PEP 460: add .format_map()
>>
>> files:
>>   pep-0460.txt |  6 +++++-
>>   1 files changed, 5 insertions(+), 1 deletions(-)
>>
>>
>> diff --git a/pep-0460.txt b/pep-0460.txt
>> --- a/pep-0460.txt
>> +++ b/pep-0460.txt
>> @@ -24,12 +24,16 @@
>>    similar in syntax to ``str.format()`` (accepting positional as well as
>>    keyword arguments).
>>
>> +* ``bytes.format_map(...)`` and ``bytearray.format_map(...)`` for an
>> +  API similar to ``str.format_map(...)``, with the same formatting
>> +  syntax and semantics as ``bytes.format()`` and ``bytearray.format()``.
>> +
>>
>>  Rationale
>>  =========
>>
>>  In Python 2, ``str % args`` and ``str.format(args)`` allow the formatting
>> -and interpolation of bytes strings.  This feature has commonly been used
>> +and interpolation of bytestrings.  This feature has commonly been used
>>  for the assembling of protocol messages when protocols are known to use
>>  a fixed encoding.
>>
>>
>>
>>
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>
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-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia