PEP 526 - var annotations and the spirit of python
steve+comp.lang.python at pearwood.info
Thu Jul 5 06:04:13 EDT 2018
On Thu, 05 Jul 2018 09:17:20 +0200, Christian Gollwitzer wrote:
> Am 04.07.18 um 17:31 schrieb Steven D'Aprano:
>> On Wed, 04 Jul 2018 13:48:26 +0100, Bart wrote:
>>> Presumably one type hint applies for the whole scope of the variable,
>>> not just the one assignment.
>> You know how in C you can write
>> int x = 1; # the type applies for just this one assignment x =
>> 2.5; # perfectly legal, right?
> Not sure what point you are trying to make, but your example compiles in
> C, if you replace the '#' comment sign with '//'.
But... it compiles? Seriously?
> Only it doesn't do
> what you might think: the 2.5 is down-converted to an integer, therefore
> x will be 2 in the end. There will be a compiler warning but no error.
Sometimes I wonder how C programmers manage to write a bug-free "Hello
World" program. No wonder it is described as a type-unsafe language or a
I understand upcasting ints to floats, that's cool (even if a few
languages take a hard line on that too, I don't). I understand Python's
dynamic typing approach. I don't understand C requiring type
declarations, then down-casting floats to integers.
At least it shows a warning. But hell, who pays attention to C compiler
warnings? There's *so many of them*.
(And I bet that by default the warning is disabled, amirite?)
"Ever since I learned about confirmation bias, I've been seeing
it everywhere." -- Jon Ronson
More information about the Python-list