[Python-ideas] Idea for new multi-line triple quote literal

[Daniel Robinson]

There is another problem with running dedent on docstrings, I believe: a PEP
257 <http://www.python.org/dev/peps/pep-0257/> compliant docstring with a
summary line won't dedent at all, since the first line lacks indentation.

If you wanted to automatically clean docstrings, I think you would want to
use the trim(docstring) function from PEP 257, rather than dedent. But I'm
guessing there was a reason this has not been done before.

On Mon, Jul 1, 2013 at 5:05 AM, Nick Coghlan <ncoghlan at gmail.com> wrote:

> On 1 July 2013 11:57, Guido van Rossum <guido at python.org> wrote:
>
>> On Sun, Jun 30, 2013 at 6:47 PM, Nick Coghlan <ncoghlan at gmail.com> wrote:
>> > On 1 July 2013 11:09, Steven D'Aprano <steve at pearwood.info> wrote:
>> >> but in either case, I think the choice of --- as delimiter is ugly and
>> >> arbitrary, and very likely is ambiguous (currently, x = ---1 is legal
>> code).
>> >> Similar suggestions to this have been made many times before, you
>> should
>> >> search the archives:
>> >>
>> >> http://mail.python.org/mailman/listinfo/python-ideas
>> >
>> > I'm still partial to the idea of offering textwrap.indent() and
>> > textwrap.dedent() as string methods.
>> >
>> > 1. You could add a ".dedent()" at the end of a triple quoted string
>> > for this kind of problem. For a lot of code, the runtime cost isn't an
>> > issue.
>> > 2. A JIT would definitely be able to avoid recalculating the result
>> every time
>> > 3. Even CPython may eventually gain constant folding for that kind of
>> > method applied directly to a string literal
>> > 4. I dedent and indent long strings more often than I capitalize,
>> > center, tab expand, or perform various other operations which already
>> > grace the str type as methods.
>>
>> That's a compelling argument. Let's do it. (Assuming the definition of
>> exactly how to indent or dedent is not up for discussion -- if there
>> are good reasons to disagree with textwrap now's the time to bring it
>> up.)
>>
>
> The only slight quirk that occurred to me is that if dedent is a method,
> people will probably want to use them with docstrings, and the compiler
> currently doesn't allow that.
>
> There are then two options for changing the compiler (if we decide we want
> to allow for "neat" docstrings):
>
> 1. Implicitly call dedent on docstrings at compilation time (feasible with
> dedent as a method).
> 2. Allow method calls on docstrings without breaking docstring detection
>
> It's technically a separate question from the decision on whether or not
> to add the methods, but I figured it was worth bringing up. Touching the
> methods of a builtin *and* possibly the compiler behaviour as well is
> likely enough to nudge the idea into PEP territory.
>
> Cheers,
> Nick.
>
> --
> Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
>
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