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

[INADA Naoki]

I have some php experiment. Using dot for string concatenation cause
readability hazard.

func("foo", "bar". "bazz", "spam". "egg")


On Thu, May 16, 2013 at 10:40 PM, MRAB <python at mrabarnett.plus.com> wrote:

> On 16/05/2013 08:08, Serhiy Storchaka wrote:
>
>> 10.05.13 21:48, Guido van Rossum написав(ла):
>>
>>> I just spent a few minutes staring at a bug caused by a missing comma
>>> -- I got a mysterious argument count error because instead of foo('a',
>>> 'b') I had written foo('a' 'b').
>>>
>>> This is a fairly common mistake, and IIRC at Google we even had a lint
>>> rule against this (there was also a Python dialect used for some
>>> specific purpose where this was explicitly forbidden).
>>>
>>> Now, with modern compiler technology, we can (and in fact do) evaluate
>>> compile-time string literal concatenation with the '+' operator, so
>>> there's really no reason to support 'a' 'b' any more. (The reason was
>>> always rather flimsy; I copied it from C but the reason why it's
>>> needed there doesn't really apply to Python, as it is mostly useful
>>> inside macros.)
>>>
>>
>> As was said before the '+' operator has less priority than the '%'
>> operator and an attribute access, i.e. it requires parenthesis in some
>> cases. However parenthesis introduce a noise and can cause other types
>> of errors.
>>
>>  [snip]
> I wonder whether we could use ".". Or would that be too confusing?
>
>
>  In all cases only multiline implicit string literal concatenation cause
>> problem. What if forbid implicit string literal concatenation only
>> between string literals on different physical lines? A deliberate string
>> literal concatenation can be made with explicit line joining.
>>
>>           raise ValueError('Type names and field names must be valid '\
>>                            'identifiers: %r' % name)
>>
>>            raise ValueError('Type names and field names must be valid ' .
>
>                            'identifiers: %r' % name)
>
>>
>>           raise ValueError('{} not bottom-level directory in '\
>>                            '{!r}'.format(_PYCACHE, path))
>>
>>            raise ValueError('{} not bottom-level directory in ' .
>                            '{!r}'.format(_PYCACHE, path))
>
>
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-- 
INADA Naoki  <songofacandy at gmail.com>
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