On 28 June 2017 at 18:54, Paul Moore <p.f.mo...@gmail.com> wrote: > On 28 June 2017 at 05:30, Terry Reedy <tjre...@udel.edu> wrote: >> A counter-argument is that there are other itertools that deserve promotion, >> by usage, even more. But we need to see comparisons from more that one >> limited corpus. > > Indeed. I don't recall *ever* using itertools.chain myself. I'd be > interested in seeing some usage stats to support this proposal. As an > example, I see 8 uses of itertools.chain in pip and its various > vendored packages, as opposed to around 30 uses of map (plus however > many list comprehensions are used in place of maps). On a very brief > scan, it looks like the various other itertools are used less than > chain, but with only 8 uses of chain, it's not really possible to read > anything more into the relative frequencies.
The other thing to look for would be list() and list.extend() calls. I know I use those quite a bit in combination with str.join, where I don't actually *need* a list, it's just currently the most convenient way to accumulate all the components I'm planning to combine. And if you're converting from Python 2 code, then adding a few list() calls in critical places in order to keep the obj.extend() calls working is likely to be easier in many cases than switching over to using itertools.chain. For simple cases, that's fine (since a list of direct references will be lower overhead than accumulating a chain of short iterables), but without builtin support for iterator concatenation, it's currently a nonlocal refactoring (to add the "from itertools import chain" at the top of the file) to switch completely to the "pervasive iterators" model when folks actually do want to do that. Cheers, Nick. -- Nick Coghlan | ncogh...@gmail.com | Brisbane, Australia _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/
