On 2018 May 11 , at 7:37 a, Rhodri James
wrote: On 11/05/18 11:14, Jacco van Dorp wrote:
Optimizing syntax for space makes sense for "mathematical" notation since it's commonly written by hand, but putting space above readability in a programming language design feels like a skewmorphism. You are assuming "given" to improve readability, where I stated ":= is
2018-05-11 11:56 GMT+02:00 João Santos
: perfectly clear ", at least in my opinion. Therefore, since clarity is already achieved, the rest is clutter that reduces readability. I respectfully disagree with your opinion (i.e. you're wrong :-)
Consider:
while (cmd := get_command()).token != CMD_QUIT: cmd.do_something()
vs:
while cmd.token != CMD_QUIT given cmd = get_command(): cmd.do_something()
I find I write code like this[*] a fair bit, since my major use for Python is to write remote monitors for embedded kit, so it's pretty much a real world example. I don't find the first version using ":=" to be perfectly clear, in fact I think it's rather ugly. That may be partly the same reaction that many of us had to the asymmetry of assignment expressions in (over-)complicated comprehensions. The second version using "given" reads much more naturally to the mathematician in me, and not too badly to my English half either.
I would write this using a for loop and the two-argument form of iter: for cmd in iter(get_command, ''): if cmd.token == CMD_QUIT: break cmd.do_something() or from itertools import take while for cmd in takewhile(lambda x: x.token != CMD_QUIT, iter(get_command, '')): cmd.do_something() Depending on what get_command actually returns, you might be able to construct a valid sentinel that doesn't require an explicit test of cmd.token. (This reminds that I wish ``iter`` could take a predicate instead of a sentinel as its second argument. Then you could just write for cmd in iter(get_command, lambda x: x.token == CMD_QUIT): cmd.do_something() ) -- Clint