On Sun, Jun 25, 2017 at 3:06 PM, lucas via Python-ideas < python-ideas@python.org> wrote:
> I often use generators, and itertools.chain on them. > What about providing something like the following: > > a = (n for n in range(2)) > b = (n for n in range(2, 4)) > tuple(a + b) # -> 0 1 2 3 > > This, from user point of view, is just as how the > __add__ operator works on lists and tuples. > Making generators works the same way could be a great way to avoid calls > to itertools.chain everywhere, and to limits the differences between > generators and other "linear" collections. > > I think a convenient syntax for chaining iterables and sequences would be very useful in Python 3, because there has been a shift from using lists by default to using views to dict keys and values, range objects etc. Having to add an import for a basic operation that used to just work with the + operator feels like a regression to many. It's not really clear if you will be able to implement this, but if you can find a syntax that gets accepted, I think using the same type as itertools.chain might be a good starting point, although the docs should not promise to return that exact type so that support for __getitem__ etc. could be added in the future for cases where the chained iterables are Sequences. -- Koos > I do not know exactly how to implement that (i'm not that good at C, nor > CPython source itself), but by seeing the sources, > i imagine that i could do something like the list_concat function at > Objects/listobject.c:473, but in the Objects/genobject.c file, > where instead of copying elements i'm creating and initializing a new > chainobject as described at Modules/itertoolsmodule.c:1792. > > (In pure python, the implementation would be something like `def > __add__(self, othr): return itertools.chain(self, othr)`) > > Best regards, > --lucas > > > _______________________________________________ > Python-ideas mailing list > Python-ideas@python.org > https://mail.python.org/mailman/listinfo/python-ideas > Code of Conduct: http://python.org/psf/codeofconduct/ > > -- + Koos Zevenhoven + http://twitter.com/k7hoven +
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