[Python-Dev] sum(...) limitation

Alexander Belopolsky alexander.belopolsky at gmail.com
Sat Aug 9 21:20:42 CEST 2014


On Sat, Aug 9, 2014 at 1:08 AM, Steven D'Aprano <steve at pearwood.info> wrote:

> We wouldn't be having
> these interminable arguments about using sum() to concatenate strings
> (and lists, and tuples) if the & operator was used for concatenation and
> + was only used for numeric addition.
>

But we would probably have a similar discussion about all(). :-)

Use of + is consistent with the use of * for repetition.  What would you
use use for repetition if you use & instead?

Compare, for example

s + ' ' * (n - len(s))

and

s & ' ' * (n - len(s))

Which one is clearer?

It is sum() that need to be fixed, not +.  Not having sum([a, b])
equivalent to a + b for any a, b pair is hard to justify.
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