[Python-ideas] Briefer string format

[Bruce Leban]

Automatically injecting from the locals or globals is a nice source of
bugs. Explicit is better than implicit, especially in case where it can
lead to security bugs.

-1

--- Bruce
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On Sun, Jul 19, 2015 at 4:35 PM, Mike Miller <python-ideas at mgmiller.net>
wrote:

> Hi,
>
> Ok, I kept the message brief because I thought this subject had previously
> been discussed often.  I've expanded it to explain better for those that
> are interested.
>
> ---
>
> Needed to whip-up some css strings, took a look at the formatting I had
> done
> and thought it was pretty ugly.  I started with the printf style, and had
> pulled out the whitespace as vars in order to have a minification option:
>
>     csstext += '%s%s%s{%s' % (nl, key, space, nl)
>
> Decent but not great, a bit hard on the eyes.  So I decided to try
> .format():
>
>     csstext += '{nl}{key}{space}{{{nl}'.format(**locals())
>
> This looks a bit better if you ignore the right half, but it is longer and
> not
> as simple as one might hope.  It is much longer still if you type out the
> variables needed as kewword params!  The '{}' option is not much
> improvement
> either.
>
>    csstext += '{nl}{key}{space}{{{nl}'.format(nl=nl, key=key, ...  # uggh
>    csstext += '{}{}{}{{{}'.format(nl, key, space, nl)
>
> I've long wished python could format strings easily like bash or perl do,
> ...
> and then it hit me:
>
>     csstext += f'{nl}{key}{space}{{{nl}'
>
> An "f-formatted" string could automatically format with the locals dict.
> Not
> yet sure about globals, and unicode only suggested for now.  Perhaps could
> be
> done directly to avoid the .format() function call, which adds some
> overhead
> and tends to double the length of the line?
>
> I remember a GvR talk a few years ago giving a 'meh' on .format() and have
> agreed, using it only when I have a very large or complicated
> string-building
> need, at the point where it begins to overlap Jinja territory.  Perhaps
> this is
> one way to make it more comfortable for everyday usage.
>
> I've seen others make similar suggestions, but to my knowledge they didn't
> include this pleasing brevity aspect.
>
> -Mike
>
>
>
> On 07/19/2015 04:27 PM, Eric V. Smith wrote:
>
>> On Jul 19, 2015, at 7:12 PM, Mike Miller <python-ideas at mgmiller.net>
>> wrote:
>>
>>>
>>> Have long wished python could format strings easily like bash or perl
>>> do, ...
>>> and then it hit me:
>>>
>>>     csstext += f'{nl}{selector}{space}{{{nl}'
>>>
>>> (This script included whitespace vars to provide a minification option.)
>>>
>>> I've seen others make similar suggestions, but to my knowledge they
>>> didn't
>>> include this pleasing brevity aspect.
>>>
>>
>> What would this do? It's not clear from your description.
>>
>> Eric.
>>
>>
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