[Python-ideas] Briefer string format

[Ryan Gonzalez]

On August 3, 2015 9:08:52 AM CDT, Steven D'Aprano <steve at pearwood.info> wrote:
>On Sun, Aug 02, 2015 at 10:43:03PM -0400, Eric V. Smith wrote:
>> On 8/2/2015 7:46 PM, Mike Miller wrote:
>> > Hi,
>> > 
>> > I don't understand how we got to arbitrary expressions.
>> 
>> I think here:
>> https://mail.python.org/pipermail/python-ideas/2015-July/034701.html
>> 
>> > There was probably an edge case or two, but I wasn't expecting
>> > str(eval(s)) to be the answer, and one I'm not sure I'd want.
>> 
>> As I pointed out earlier, it's not exactly str(eval(s)). Also, what's
>> your concern with the suggested approach? There are no security
>concerns
>> as there would be with eval-ing arbitrary strings.
>
>Language features should be no more powerful than they need to be. It 
>isn't just *security* that we should be concerned about, its also about
>
>readability, learnability, the likelihood of abuse by writing 
>unmaintainable Perlish one-liners, and the general increase in 
>complexity.
>
>Or to put it another way... YAGNI.
>
>We started of with a fairly simple and straightforward feature request:
>
>to make it easy to substitute named variables in format strings. We 
>ought to be somewhat cautious about accepting even that limited
>version. 
>After all, hundreds of languages don't have such a feature, and Python 
>worked perfectly well without it for over 20 years. This doesn't add 
>anything to the language that cannot already be done with % and 
>str.format().
>
>But suddenly we've gone from a feature request that has been routinely 
>denied many times in the past (having variables be automatically 
>substituted into strings), to full-blown evaluation of arbitrarily 
>complex expressions being discussed as if it were a done-deal.
>
>I've heard of the trick of asking for a pony if you actually want a 
>puppy, but this is the first time I've seen somebody ask for a puppy
>and 
>be given a thoroughbred.
>
>Anyway, there's no harm done, since this is going through the PEP 
>process. It just strikes me as so unlike the usual conservatism, 
>particularly when it comes to syntax changes, that it surprised me. 
>Perhaps somebody slipped something in the water? :-)

Nah, we've just reached the maximum number of we can use % formatting before slowly drifting away into madness.


-- 
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