PEP 378: Format Specifier for Thousands Separator

[Steven D'Aprano]

On Tue, 21 May 2013 14:53:54 -0500, Andrew Berg wrote:

> On 2013.05.21 14:26, Mark Lawrence wrote:

>> Please stop perpetuating this myth, see
>> http://mail.python.org/pipermail/python-dev/2012-February/116789.html
>> and http://bugs.python.org/issue14123
>> 
> What myth? 

The myth that % string formatting is deprecated. It is not deprecated.

> People should indeed be using .format(), 

If it is useful to them, and not too slow, or indeed if they merely want 
to. And if not, then not.

This is a good case where the original poster *should* use str.format, 
since it does exactly what he wants, and % does not. Python gives you 
many tools, and the wise man uses the right tool for the job. Sometimes 
that is % and sometimes it is str.format and sometimes it is 
string.Template.

That str.format looks like Java is irrelevant. Method call syntax is 
common in Python, and is not original to Java. Besides, Python looks like 
many languages: some parts look like Java, some parts look like C, some 
parts remind me of functional languages like Lisp and Haskell, and some 
parts look like Algol or Pascal.


> but no one said % formatting was going away soon.

True, but only for the definition "no one = all the people who insist 
that % is deprecated, or soon to be deprecated".


> Also, the suggested change to the docs
> wasn't made and the issue is closed. The current docs do not say that %
> formatting isn't going to be deprecated, but it does mention its caveats
> and suggests .format(). If you are trying to say that % formatting will
> never ever go away, then you are wrong. It is highly unlikely to go away
> in a 3.x release, but /may/ get phased out in Python 4.0.

What happens in Python 4000 is irrelevant. If somebody is trying to 
"future proof" their code for a version that *may never exist*, and if it 
does exist is likely to be six or eight years away from even starting the 
design phase, they are wasting their time. It is hard enough to track a 
moving target, it is impossible to track a target that isn't even a gleam 
in GvR's eye yet.



-- 
Steven