[Python-ideas] Re: execute function on iterator items without changing or consuming iterator

this seems nice. It just seems that the obvious way to do it would be: def tap(iter_, func): for item in iter_: func(item) yield item I think it can be nice, but more as cookbook material than an actual itertools function. On Sun, 25 Oct 2020 at 14:38, <2QdxY4RzWzUUiLuE@potatochowder.com> wrote:

On 2020-10-25 at 16:34:14 +0000, George Harding wrote:

...

some_iter = map(lambda x: x if print(x) else x, some_iter)

The tuple has a ~50% overhead, the case statement ~15%, compared to the generator.

def print_first(x): print(x) return x new_iter = map(print_first, some_iter)

No extranous tuple, no extranous case stament. Newlines are cheap these days. The call to print, however, is possibly unbounded in time and space.

If you really want to go overboard, put something like the following peeker function into your personal toolbox (untested):

def peeker(function): def peeker(x): function(x) return x return peeker

And use it like this:

new_iter = map(peeker(print), some_iter) _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-leave@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/RG2ZQD... Code of Conduct: http://python.org/psf/codeofconduct/