[Python-Dev] Re: PEP 647 (type guards) -- final call for comments

2021年2月14日 15:59:52 -0800

On 2/14/21 2:34 PM, Guido van Rossum wrote:
On Sun, Feb 14, 2021 at 12:51 PM David Mertz <[email protected] <mailto:[email protected]>> wrote:
 On Sun, Feb 14, 2021, 2:53 PM Gregory P. Smith <[email protected]
 <mailto:[email protected]>> wrote:
 *TL;DR of my TL;DR* - Not conveying bool-ness directly in the
 return annotation is my only complaint. A BoolTypeGuard
 spelling would alleviate that.
 This is exactly my feeling as well. In fact, I do not understand
 why it cannot simply be a parameterized Bool. That would avoid all
 confusion. Yes, it's not the technical jargon type system
 designers use... But the existing proposal moves all the mental
 effort to non-experts who may never use type checking tools.
But note that 'bool' in Python is not subclassable.
No, but this hypothetical 'Bool'--presumably added to typing.py--might well be.
Cheers,
//arry/
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