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

[MRAB]

On 16/05/2013 18:26, Bruce Leban wrote:
>
> On Thu, May 16, 2013 at 9:57 AM, Christian Tismer <tismer at stackless.com
> <mailto:tismer at stackless.com>> wrote:
>
>     The "&" is not a valid operator on strings and looks pretty much like
>     gluing parts together. It is better than the "\" that just escapes
>     the newline
>     and cannot take comments.
>
>
> I don't like something that is a standard operator becoming special
> syntax. While it's true that string & string is not valid, it's not the
> case that string & ... is not valid. I dislike dot for the same reason.
> It's confusing that these would do different things:
>
>      'abc' & 'def'
>      ('abc') & 'def'
>
> I like the \ idea because it's clearly syntax and not an operator, but
> the fact that it doesn't work with comments is annoying since one reason
> to break a string is to insert comments. I don't like that spaces after
> the \ are not allowed because trailing spaces are invisible to me but
> not to the parser. So what if the rule for trailing \ was changed to:
>
>     The \ continuation character may be followed by white space and a
>     comment. If a comment is present, there must be at least one
>     whitespace character between the \ and the comment.
>
>
Why do you say """there must be at least one whitespace character
between the \ and the comment"""?

> That is:
>
> x = [  # THIS WOULD BE ALLOWED
>      'abc'   \
>      'def'   \   # not the python keyword
>      'ghi'
> ]
>
> x = [  # THIS WOULD BE AN ERROR
>      'abc'   \
>      'def' # a comment but no continuation \
>      'ghi'
> ]
>
> One thing I like about using \ is that it already works (aside from my
> proposed comment change). So anyone wanting to write
> forward/backward-compatible code can just add the \s now. If you want to
> start enforcing the restriction, just use from __future__ import
> explicit_string_continuation.
>