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  1. Qt for Python
  2. PYSIDE-2541

Fix type inference for QmlElement

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Details

    • Suggestion
    • Resolution: Unresolved
    • P4: Low
    • None
    • 6.6.2
    • Type hints
    • None

    • VSCode + Pylance, Python 3.10, PySide 6.6

    Description

      Currently, using the QmlElement decorator erases type information, because it is defined to return object/Any. Users can work around this issue by wrapping the decorator with a generic function, for example:

      from PySide6.QtCore import QObject
from PySide6.QtQml import QmlElement

@QmlElement
class Erased(QObject):
    pass

E = TypeVar("E")
def TypedQmlElement(arg: E) -> E:
    return QmlElement(arg)

@TypedQmlElement
class NotErased(QObject):
    pass

def do_something():
    return Erased(), NotErased()

erased, not_erased = do_something()
# Pylance shows "erased: Any, not_erased: NotErased"

      This is fixed either by adding the typevar to the .pyi file instead, or apparently by removing the type hints entirely:

      E = TypeVar("E")
def QmlElement(arg__1: E) -> E: ... 
# or
def QmlElement(arg__1): ...

      Attachments

        Issue Links

          duplicates

          Bug - A problem which impairs or prevents the functions of the product. PYSIDE-2365 @QmlElement decorator doesn't return original type

          • Not Evaluated - Not yet evaluated/prioritized
          • Closed
          is duplicated by

          Bug - A problem which impairs or prevents the functions of the product. PYSIDE-2947 Type stub for QmlElement (and others) obscure decorated type from type checkers

          • Not Evaluated - Not yet evaluated/prioritized
          • Closed
          relates to

          Suggestion - Public suggestions PYSIDE-2767 MyPy/PyRight error with PySide6.QtCore.Property

          • P3: Somewhat important - Should be fixed, but doesn't affect the release in any way.
          • Closed

          Suggestion - Public suggestions PYSIDE-2542 QtCore.QSettings.value should infer return type from type parameter

          • P4: Low - Would be nice to fix, but it's not very important.
          • Closed
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          Activity

            People

              ctismer Christian Tismer
              thorn132 Tim Hornick
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              4 Vote for this issue
              Watchers:
              3 Start watching this issue

              Dates

                Created:
                Updated:

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