fix `pyqtSlot` `result` parameter type and `Callable` generic #102

altendky · 2020-10-04T00:23:12Z

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PyQt5-stubs/QtCore.pyi

tests/pyqtslot.py

PyQt5-stubs/QtCore.pyi

altendky · 2020-10-04T13:20:20Z

PyQt5-stubs/QtCore.pyi

@@ -9264,7 +9264,7 @@ def oct_(s: QTextStream) -> QTextStream: ...
 def bin_(s: QTextStream) -> QTextStream: ...
 def Q_RETURN_ARG(type: typing.Any) -> QGenericReturnArgument: ...
 def Q_ARG(type: typing.Any, data: typing.Any) -> QGenericArgument: ...
-def pyqtSlot(*types: typing.Any, name: typing.Optional[str] = ..., result: typing.Optional[str] = ...) -> typing.Callable[[FuncT], FuncT]: ...
+def pyqtSlot(*types: typing.Any, name: typing.Optional[str] = ..., result: typing.Type[object] = ...) -> typing.Callable[[FuncT], FuncT]: ...


How do you feel about the typing.Type[object]. I starting with Type because I was trying to relate it to the function return type but... I didn't get that working. Maybe this should just be object/Any?

Could FuncT be made generic? I think this would work

T = TypeVar("T") FuncT = typing.TypeVar('FuncT', bound=typing.Callable[..., T]) def pyqtSlot(*types: typing.Any, name: typing.Optional[str] = ..., result: typing.Type[T] = ...) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...

However, looking at the docs:

result – the type of the result and may be a Python type object or a string that specifies a C++ type

Not sure how the C++ string would interact with this. Maybe

def pyqtSlot(*types: typing.Any, name: typing.Optional[str] = ..., result: typing.Union[typing.Type[T], str] = ...) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...

Just noticed that types has the same comment in the docs about "may be a Python type object or a string", so maybe we can be more specific than typing.Any

Did you mean "can't be more specific"? When I read this I thought you made a comment then backed away from it. I did make an effort to relate the result parameter to the return type of the typing.Callable parameter and return but failed. I could make another attempt for you to look at.

No those were two different comments. I was suggesting that we change result to use a generic. Then I noticed that types is documented in a similar fashion and remarked that we could maybe do better than its current typing.Any

For the types, they can be any types including user defined and they don't necessarily even inherit from type what with metatypes, right? (plus str) So the only thing I can think of is to try to relate it with the parameters of the wrapped callable, but mypy doesn't do that yet. There's some related PEP but I can't find it at the moment. Do you have something specific in mind here?

I'll try what you shared though it looks familiar.

Yeah you're probably right that types is as good as mypy currently allows

Here's yours along with the existing and a Protocol attempt.

https://mypy-play.net/?mypy=latest&python=3.8&gist=314620351fccbbfd297833d345b40a6d

import typing FuncT = typing.TypeVar('FuncT', bound=typing.Callable[..., typing.Any]) def pyqtSlot(*types: typing.Any, name: typing.Optional[str] = ..., result: typing.Any = ..., revision: int = ...) -> typing.Callable[[FuncT], FuncT]: ... T = typing.TypeVar("T") FuncT2 = typing.TypeVar('FuncT2', bound=typing.Callable[..., T]) def pyqtSlot2(*types: typing.Any, name: typing.Optional[str] = ..., result: typing.Type[T] = ...) -> typing.Callable[[FuncT2[T]], FuncT2[T]]: ... T_covariant = typing.TypeVar("T_covariant", covariant=True) class P(typing.Protocol, typing.Generic[T_covariant]): def __call__(self, *args: typing.Any, **kwargs: typing.Any) -> T_covariant: ... def pyqtSlot3(*types: typing.Any, name: typing.Optional[str] = ..., result: typing.Type[T_covariant] = ...) -> typing.Callable[[P[T_covariant]], P[T_covariant]]: ... def f(s: str, i: int) -> float: ... reveal_type(pyqtSlot(result=float)(f)) reveal_type(pyqtSlot2(result=float)(f)) reveal_type(pyqtSlot3(result=float)(f))

main.py:11: error: Type variable "FuncT2" used with arguments main.py:25: note: Revealed type is 'def (s: builtins.str, i: builtins.int) -> builtins.float' main.py:26: error: Value of type variable "FuncT2" of function cannot be "Callable[[str, int], float]" main.py:26: note: Revealed type is 'def (s: builtins.str, i: builtins.int) -> builtins.float' main.py:27: note: Revealed type is 'main.P[builtins.float*]' main.py:27: error: Argument 1 has incompatible type "Callable[[str, int], float]"; expected "P[float]" Found 3 errors in 1 file (checked 1 source file)

I don't think we get to make a generic typevar.

Is there a reason we need to make FuncT a TypeVar?

import typing S = typing.TypeVar("S") T = typing.TypeVar("T") FuncT = typing.Callable[..., S] def pyqtSlot(*types: typing.Any, name: typing.Optional[str] = ..., result: typing.Type[T] = ...) -> typing.Callable[[FuncT[T]], FuncT[T]]: ... def f(s: str, i: int) -> float: ... reveal_type(pyqtSlot(result=float)(f))

main.py:13: note: Revealed type is 'def (*Any, **Any) -> builtins.float*'

def f(s: str, i: int) -> float: ... reveal_type(pyqtSlot(result=bool)(f))

main.py:13: note: Revealed type is 'def (*Any, **Any) -> builtins.bool*' main.py:13: error: Argument 1 has incompatible type "Callable[[str, int], float]"; expected "Callable[..., bool]" Found 1 error in 1 file (checked 1 source file)

You win (I think), thanks.

PyQt5-stubs/QtCore.pyi

BryceBeagle · 2020-10-04T17:11:43Z

PyQt5-stubs/QtCore.pyi

@@ -9264,7 +9264,7 @@ def oct_(s: QTextStream) -> QTextStream: ...
 def bin_(s: QTextStream) -> QTextStream: ...
 def Q_RETURN_ARG(type: typing.Any) -> QGenericReturnArgument: ...
 def Q_ARG(type: typing.Any, data: typing.Any) -> QGenericArgument: ...
-def pyqtSlot(*types: typing.Any, name: typing.Optional[str] = ..., result: typing.Optional[str] = ...) -> typing.Callable[[FuncT], FuncT]: ...
+def pyqtSlot(*types: typing.Any, name: typing.Optional[str] = ..., result: typing.Type[object] = ...) -> typing.Callable[[FuncT], FuncT]: ...


Could FuncT be made generic? I think this would work

T = TypeVar("T") FuncT = typing.TypeVar('FuncT', bound=typing.Callable[..., T]) def pyqtSlot(*types: typing.Any, name: typing.Optional[str] = ..., result: typing.Type[T] = ...) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...

However, looking at the docs:

result – the type of the result and may be a Python type object or a string that specifies a C++ type

Not sure how the C++ string would interact with this. Maybe

def pyqtSlot(*types: typing.Any, name: typing.Optional[str] = ..., result: typing.Union[typing.Type[T], str] = ...) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...

BryceBeagle · 2020-10-04T17:12:33Z

PyQt5-stubs/QtCore.pyi

@@ -9264,7 +9264,7 @@ def oct_(s: QTextStream) -> QTextStream: ...
 def bin_(s: QTextStream) -> QTextStream: ...
 def Q_RETURN_ARG(type: typing.Any) -> QGenericReturnArgument: ...
 def Q_ARG(type: typing.Any, data: typing.Any) -> QGenericArgument: ...
-def pyqtSlot(*types: typing.Any, name: typing.Optional[str] = ..., result: typing.Optional[str] = ...) -> typing.Callable[[FuncT], FuncT]: ...
+def pyqtSlot(*types: typing.Any, name: typing.Optional[str] = ..., result: typing.Type[object] = ...) -> typing.Callable[[FuncT], FuncT]: ...


Just noticed that types has the same comment in the docs about "may be a Python type object or a string", so maybe we can be more specific than typing.Any

altendky · 2020-10-06T12:59:48Z

Do you think we should try to do more here now?

BryceBeagle · 2020-10-06T16:49:22Z

Did you see my comment about making FuncT generic?

BryceBeagle · 2020-10-07T06:27:36Z

Sorry not trying to drag this PR on and on again, but I think we need this for the overloads:

@typing.overload
def pyqtSlot(*types: typing.Any) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...
@typing.overload
def pyqtSlot(*types: typing.Any, name: str) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...
@typing.overload
def pyqtSlot(*types: typing.Any, result: typing.Union[typing.Type[T], str]) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...
@typing.overload
def pyqtSlot(*types: typing.Any, revision: int) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...
@typing.overload
def pyqtSlot(*types: typing.Any, name: str, result: typing.Union[typing.Type[T], str]) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...
@typing.overload
def pyqtSlot(*types: typing.Any, name: str, revision: int) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...
@typing.overload
def pyqtSlot(*types: typing.Any, result: typing.Union[typing.Type[T], str], revision: int) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...
@typing.overload
def pyqtSlot(*types: typing.Any, name: str, result: typing.Union[typing.Type[T], str], revision: int) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...

What I changed:

Added overloads for each combination of all three optional arguments. Note that they're not optional... just overloads *. This is pretty verbose, but I don't know of a better option.
Removed the Optional-ality of the str arguments
Removed ... defaults from arguments because they don't actually have defaults
Combined the result types into a Union because the Union-ization doesn't affect the return type/other arguments

* Note: This contradicts the documentation here where the later arguments are in ever-nesting brackets. The documentation implies that you can't use revision without using result but this doesn't appear to be the case. Some of the examples in the docs even contradict the specification.

>>> pyqtSlot(int, name=None)

TypeError: pyqtSlot() argument 1 must be str, not None

Side note: It looks like argument 1 here is a bugged miscount on PyQt's side, as this is argument 2.

This is further contradicted pyqtSlot.__doc__:

@pyqtSlot(*types, name: Optional[str], result: Optional[str])

This is a decorator applied to Python methods of a QObject that marks them
as Qt slots.
The non-keyword arguments are the types of the slot arguments and each may
be a Python type object or a string specifying a C++ type.
name is the name of the slot and defaults to the name of the method.
result is type of the value returned by the slot.

We should probably mention this to Phil too.

This is a mess 🤦

altendky · 2020-10-07T13:15:40Z

You can't use Union there with --strict because it makes the TypeVar be <nothing>. I'll expand and commit.

https://mypy-play.net/?mypy=latest&python=3.8&flags=strict&gist=9608229557029541b9a90553bce77414

import typing


T = typing.TypeVar("T")
FuncT = typing.Callable[..., T]
@typing.overload
def pyqtSlot(*types: typing.Any) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...
@typing.overload
def pyqtSlot(*types: typing.Any, name: str) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...
@typing.overload
def pyqtSlot(*types: typing.Any, result: typing.Union[typing.Type[T], str]) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...
@typing.overload
def pyqtSlot(*types: typing.Any, revision: int) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...
@typing.overload
def pyqtSlot(*types: typing.Any, name: str, result: typing.Union[typing.Type[T], str]) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...
@typing.overload
def pyqtSlot(*types: typing.Any, name: str, revision: int) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...
@typing.overload
def pyqtSlot(*types: typing.Any, result: typing.Union[typing.Type[T], str], revision: int) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...
@typing.overload
def pyqtSlot(*types: typing.Any, name: str, result: typing.Union[typing.Type[T], str], revision: int) -> typing.Callable[[FuncT[T]], FuncT[T]]: ...

@pyqtSlot(str, result='int')
def func_str(s: str) -> int:
    return 42

main.py:6: error: An overloaded function outside a stub file must have an implementation
main.py:23: error: Argument 1 has incompatible type "Callable[[str], int]"; expected "Callable[..., <nothing>]"
Found 2 errors in 1 file (checked 1 source file)

BryceBeagle

Actually we probably also want to update the changelog too

BryceBeagle · 2020-10-07T16:15:45Z

fix `pyqtSlot` parameter typing and overloads

CHANGELOG.md

fix `pyqtSlot` `result` parameter type and `Callable` generic

…t-tools#102

altendky added 2 commits October 3, 2020 20:22

fix pyqtSlot result parameter type and Callable generic

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Update CHANGELOG.md

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altendky mentioned this pull request Oct 4, 2020

Enable strict for mypy #99

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altendky commented Oct 4, 2020

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Merge branch 'master' into pyqtslot_fixup

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altendky added 3 commits October 4, 2020 13:55

Update QtCore.pyi

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Add revision parameter to pyqtSlot

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Merge branch 'master' into pyqtslot_fixup

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alias over typevar

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expand pyqtSlot overloads instead of inaccurate Optional

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altendky merged commit 70238e1 into python-qt-tools:master Oct 7, 2020

altendky deleted the pyqtslot_fixup branch October 7, 2020 22:49

bluebird75 pushed a commit to bluebird75/PyQt5-stubs that referenced this pull request Aug 24, 2021

Merge pull request python-qt-tools#102 from altendky/pyqtslot_fixup

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fix `pyqtSlot` `result` parameter type and `Callable` generic

bluebird75 added a commit to bluebird75/PyQt5-stubs that referenced this pull request Apr 26, 2022

Add a few more example of pyqtSlot() usage, inspiration from python-q…

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…t-tools#102

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fix `pyqtSlot` `result` parameter type and `Callable` generic #102

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fix pyqtSlot result parameter type and Callable generic #102

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fix `pyqtSlot` `result` parameter type and `Callable` generic #102

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