Op di 31 jul. 2018 20:49 schreef Jonathan Fine <jfine2358@gmail.com>:
David Mertz wrote:
`spam?.eggs?.cheese?.aardvark` is NOT redundant for `spam?.eggs.cheese.aardvark`. The two expressions simply do different things [...]
I agree, assuming ?. is a binary operator.
It isn't. Given this, in Python (+
PEP 505) one can write
tmp = spam ?. eggs val1 = tmp ?. cheese ?. aardvark # For spam?.eggs?.cheese?.aardvark val2 = tmp . cheese . aardvark # For spam?.eggs.cheese.aardvark
Nope, the introduction of the tmp variable changed the semantics. It isn't a "chain" anymore so it breaks shortcutting. To be honest I didn't get this either until it was pointed out to me
No special knowledge of PEP 505 is needed. If val1 is always equal to val2, then the dot and None-dot operators must be the same. From the assumptions, this is something that can be mathematically proved.
And false.
By the way, there's a widely used programming language in which val = a.method() and tmp = a.method val = tmp() are not always equivalent. Can you guess which language it is?
Javascript. I suppose in the same way as x+2 and x*2 are " not always" equivalent. Stephan
The answer is in:
https://www.slideshare.net/jonathanfine/javascript-the-easiest-quiz-in-the-w... (question 6: Dot binds).
I'll now go back to following the example of Steve Bower and Raymond Hettinger, which in my words is to wait until we have proper cover for the BDFL's vacation.
-- Jonathan _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/