On Fri, May 10, 2013 at 11:48 AM, Guido van Rossum <guido@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').

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.)

Would it be reasonable to start deprecating this and eventually remove
it from the language?

I would also be happy to see this error-prone syntax go (was bitten by it a number of times in the past), but I have a practical question here:

Realistically, what does "start deprecating" and "eventually remove" means here? This is a significant backwards-compatibility breaking change that will *definitely* break existing code. So would it be removed just in "Python 4"? Or are you talking about an actual 3.x release like "deprecate in 3.4 and remove in 3.5" ?

Eli