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

[MRAB]

On 10/05/2013 20:26, Alexander Belopolsky wrote:
>
>
>
> On Fri, May 10, 2013 at 2:48 PM, Guido van Rossum <guido at python.org
> <mailto:guido at python.org>> wrote:
>
>     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').
>
>
> I had a similar experience just few weeks ago.  The bug was in a long
> list written like this:
>
> ['item11', 'item12', ..., 'item17',
>   'item21', 'item22', ..., 'item27'
>   ...
>   'item91', 'item92', ..., 'item97']
>
> Clearly the bug crept in when more items were added.   (I try to keep
> redundant commas at the end of the list to avoid this, but not everyone
> likes this style.)
>
>
>     Would it be reasonable to start deprecating this and eventually remove
>     it from the language?
>
>
> +1, but I would start by requiring () around concatenated strings.
>
I'm not so sure.

Currently, parentheses, brackets and braces effectively make Python 
ignore a newline within them.

(1
+2)

is the same as:

(1+2)

and:

[1
+2]

is the same as:

[1+2]

Under the proposal:

("a"
"b")

or:

("a" "b")

would be the same as:

("ab")

but:

["a"
"b"]

or:

["a" "b"]

would be a syntax error.