On Mon, Mar 28, 2016 at 7:49 AM, BartC <b...@freeuk.com> wrote: > On 27/03/2016 21:32, Tim Chase wrote: >> >> On 2016-03-27 14:28, Steven D'Aprano wrote: > > >>> In this case, the two lines "fnc" and "next" simply look up the >>> function names, but without actually calling them. They're not >>> quite "no-ops", since they can fail and raise NameError if the name >>> doesn't exist, but otherwise they might as well be no-ops. >> >> >> Which is actually useful. I've got some 2.4 code that reads >> >> try: >> any >> except NameError: >> def any(...): >> ... >> >> (with a similar block for all() ) >> >> I don't want to call any() or all(), I simply want to test whether >> they exist. > > > But would it have been much of an imposition to have typed: > > try: > test = any > except NameError: > def any(...): > ... > > ? (Or any of the half dozen ways there must be to test the existence of a > name.)
It shifts the uselessness to "why did you assign to that name?". While that's not too bad (and nothing like as bad as a dummy function call), it's generally reserved for the places where Python syntax mandates an assignment: for _ in range(4): next(iter) # discard the headers If you're building a linter, I would expect "name assigned to and never used" to be its own warning; but also, the try/except block hints that this isn't useless. Generally, "dummy expressions" like this are going to explicitly catch at least one exception that can be raised only in that expression (ie a really small try block). That pretty much counts as your language-level marker for conscious dummy expression usage. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
