[Python-ideas] Implicit string literal concatenation considered harmful?

[Christian Tismer]

On 11.05.13 05:37, Nick Coghlan wrote:
> On Sat, May 11, 2013 at 10:29 AM, Bruce Leban <bruce at leapyear.org> wrote:
>> I got bit by this quite recently, leaving out a comma in a long list of
>> strings and I only found the bug by accident.
>>
>> This being python "ideas" I'll throw one out.
>>
>> Add another prefix character to strings:
>>
>>      a = [m'abc'
>>           'def']   # equivalent to ['abcdef']
> As MRAB suggested, a prefix for a compile time dedent would likely be
> more useful - then you'd just use a triple quoted string and be done
> with it. The other one I occasionally wish for is a compile time
> equivalent of str.split (if we had that, we likely wouldn't see APIs
> like collections.namedtuple and enum.Enum accepting space separated
> strings).
>
> Amongst my ideas-so-farfetched-I-never-even-wrote-them-up (which is
> saying something, given some of the ideas I *have* written up) is a
> notation like:
>
>      !processor!"STRING LITERAL"
>
> Where the compile time string processors had to be registered through
> an appropriate API (probably in the sys module). Then you would just
> define preprocessors like "merge" or "dedent" or "split" or "sh" of
> "format" and get the appropriate compile time raw string->AST
> translation.
>
> So for this use case, you would do:
>
>      a = [!merge!"""\
>             abc
>             def"""
>

Ah, I see we are on the same path here.
Just not sure if it is right to move into a compile-time preprocessor
language or to just handle the most common cases with a simple
prefix?
One example is code snippets which need proper de-indentation.
I think a simple stripping of white-space in

     text = s"""
       leftmost column
         two-char indent
       """

would solve 95 % of common indentation and concatenation cases.
I don't think provision for merging is needed very often.
If text occurs deeply nested in code, then it is also quite likely to
be part of an expression, anyway.
My major use-case is text constants in a class or function that
is multiple lines long and should be statically ready to use without
calling a function.

(here an 's' as a strip prefix, but I'm not sold on that)

cheers - chris

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