Hello,
On Mon, 11 Jan 2021 13:44:45 -0800
Larry Hastings <[email protected]> wrote:
> The control-flow exclusion is for /module//attribute/ or /class
> attribute/ annotations:
>
> class C:
> if random.random() > 0.5:
> my_attr:int=3
> else:
> my_attr2:float=3.5
Ok, let's take "module attribute" as an example. Why do you think
there's anything wrong with this code:
======
import config
from .types import *
if config.SUPPORT_BIGINT:
var: bigint = 1
else:
var: int64 = 1
======
> Your example doesn't define any module attributes or class attributes
> inside flow control statements, so that code should work fine.
> (Defining functions/methods inside flow control statements isn't a
> problem.)
PEP649 criticizes PEP563's approach with big words like "It requires
Python implementations to stringize their annotations. This is
surprising behavior — unprecedented for a language-level feature." But
itself devolves to clauses like:
>>> It seems reasonable to declare that both are at the very least
>>> unsupported, and their use results in undefined behavior. It might
>>> be worth making a small effort to explicitly prohibit them with
>>> compile-time checks.
Isn't the fact that PEP563 doesn't have problems with annotations in
conditionals is a sign of PEP563 technical superiority? And its
"unprecedented" measure of storing annotations as strings is actually a
clever technical feat - it should have stored annotations as AST trees,
but such trees would take quite a lot of memory. So, PEP563 smartly
went to store those ASTs in a serialized format. So, those strings
aren't strings, but serialized ASTs.
Overall 2 comments/questions:
1. Was there an attempt to devise how to make PEP649 deal with existing
Python language features (like conditionals)?
2. As a general comment, PEP649, by placing arbitrary restrictions on
where annotations can appear, tries to dig under the foundations of
Python as a dynamic language. Which is absolutely great, it just the
PEP should be viewed as such - undermining Python's dynamic nature, as
if there's something wrong with it.
--
Best regards,
Paul mailto:[email protected]
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