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PEP 591: Adding a final qualifier to typing #990

Merged
merged 5 commits into from
Apr 13, 2019
Merged

PEP 591: Adding a final qualifier to typing #990

merged 5 commits into from
Apr 13, 2019

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msullivan
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Initial draft of proposal to add a final qualifier to the typing module

@gvanrossum gvanrossum merged commit f3b44fb into python:master Apr 13, 2019
@msullivan msullivan deleted the final branch April 13, 2019 00:18
JelleZijlstra
JelleZijlstra reviewed Apr 13, 2019
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pep-0591.rst
subclasses. (``@property`` can make an attribute read-only but
does not prevent overriding)
* Allowing a name to be used in situations where ordinarily a literal
is expected (for example as a file name for ``NamedTuple``, a tuple
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Sorry I'm late to the party, but I'm guessing "file name" is a typo for "field name".

pep-0591.rst
@final
def method(self, x=None):
...

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Perhaps say that use of final on a non-method function is an error.

pep-0591.rst
for x in [1, 2, 3]:
FOO: Final = x # Error: Cannot use Final inside a loop

error: Cannot use Final inside a loop
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Stray line

ncoghlan pushed a commit to ncoghlan/peps that referenced this pull request May 7, 2019
@msullivan @ncoghlan
PEP 591: Adding a final qualifier to typing (python#990)
c0e95a0
@sproshev
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Is it possible to use Final in type comments?

@ilevkivskyi
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Yes.

@gvanrossum
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Maybe there should be an example of that somewhere? (At least in the PEP? And even Python 3 code might want to use type comments if it's straddling with 2.7.)

@msullivan
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I'll make a PR soon

@sproshev
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In the following sample mypy does not raise an error for y:

from typing_extensions import Final

x: Final[int] = 1
x: Final[str] = "str"

def foo():
    y: Final[int] = 1
    y: Final[str] = "str"

Is it a mypy bug or this case is allowed by PEP?

@ilevkivskyi
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@sproshev How about adding an annotation to foo() or using --check-untyped-defs?

Also please don't spam in this PR. If you have questions, ask them on typing Gitter.

@MadLittleMods MadLittleMods mentioned this pull request Aug 3, 2021
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@MadLittleMods MadLittleMods mentioned this pull request Sep 8, 2021
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@msullivan @sproshev @ilevkivskyi @gvanrossum @JelleZijlstra @the-knights-who-say-ni