
On 8/2/2014 1:57 AM, Allen Li wrote:
On Fri, Aug 01, 2014 at 02:51:54PM -0700, Guido van Rossum wrote:
No. We just can't put all possible use cases in the docstring. :-)
On Fri, Aug 1, 2014 at 2:48 PM, Andrea Griffini <agriff@tin.it> wrote:
help(sum) tells clearly that it should be used to sum numbers and not strings, and with strings actually fails.
However sum([[1,2,3],[4],[],[5,6]], []) concatenates the lists.
Is this to be considered a bug?
Can you explain the rationale behind this design decision? It seems terribly inconsistent. Why are only strings explicitly restricted from being sum()ed? sum() should either ban everything except numbers or accept everything that implements addition (duck typing).
O(n**2) behavior, ''.join(strings) alternative. -- Terry Jan Reedy