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Fix various ParamSpec errors in typing #24176

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miss-islington merged 3 commits into from
Jan 11, 2021
Merged

Fix various ParamSpec errors in typing #24176

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9045a28
Paramspec -> typevar
Fidget-Spinner Jan 9, 2021
65c17cb
paramspec isn't actually keyword only
Fidget-Spinner Jan 9, 2021
bb58480
enforce keyword only arguments
Fidget-Spinner Jan 10, 2021
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paramspec isn't actually keyword only
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Fidget-Spinner committed Jan 9, 2021
commit 65c17cbe90691babd671cfc2bf1e9823fe64800e
2 changes: 1 addition & 1 deletion Doc/library/typing.rst
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Expand Up @@ -1000,7 +1000,7 @@ These are not used in annotations. They are building blocks for creating generic
for the type variable must be a subclass of the boundary type,
see :pep:`484`.

.. class:: ParamSpec(name, *, bound=None, covariant=False, contravariant=False)
.. class:: ParamSpec(name, bound=None, covariant=False, contravariant=False)

@gvanrossum gvanrossum Jan 9, 2021

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Hm. I would rather add the star to the code.

@Fidget-Spinner Fidget-Spinner Jan 10, 2021 •
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Hmm after giving it some thought, I agree. I realized ParamSpec and TypeVar have different init signatures, (TypeVar has *constraints and ParamSpec doesn't). And PEP 612 states that

However, enforcing these constraints would require enough additional implementation work that we judged this extension to be out of scope of this PEP. Fortunately the design of ParamSpecs are such that we can return to this idea later if there is sufficient demand.

so to prevent any backwards incompatibility in the future, we should enforce it, so that if we do add constraints in the future, existing code won't break.

Edit: bounds -> constraints


Parameter specification variable. A specialized version of
:class:`type variables <TypeVar>`.
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