Python.NET:如何访问接口的通用成员

Question

我正试图通过FlaUI通过Python.NET从一个接口中使用一个通用成员。

下面的C#代码工作，

// myLegacyTreeItem is a valid AutomationElement
// this works and the default action expands the tree node
myLegacyTreeItem.Patterns.LegacyIAccessible.Pattern.DoDefaultAction();

但是，下面对应的Python.NET代码不起作用，

# my_legacy_tree_item is a valid element
my_legacy_tree_item.Patterns.LegacyIAccessible.Pattern.DoDefaultAction()

我收到以下错误，

AttributeError: 'UIA3FrameworkAutomationElement' object has no attribute 'LegacyIAccessible'

我可以看到LegacyIAccessible成员正在使用泛型语法。但我想不出如何将它绑定到具体的类型。

https://github.com/FlaUI/FlaUI/blob/master/src/FlaUI.Core/FrameworkAutomationElementBase.Patterns.cs

using FlaUI.Core.Patterns;

namespace FlaUI.Core
{
    public abstract partial class FrameworkAutomationElementBase : FrameworkAutomationElementBase.IFrameworkPatterns
    {
        private IAutomationPattern<IAnnotationPattern> _annotationPattern;
        private IAutomationPattern<IDockPattern> _dockPattern;
        private IAutomationPattern<IDragPattern> _dragPattern;
        private IAutomationPattern<IDropTargetPattern> _dropTargetPattern;
        private IAutomationPattern<IExpandCollapsePattern> _expandCollapsePattern;
        private IAutomationPattern<IGridItemPattern> _gridItemPattern;
        private IAutomationPattern<IGridPattern> _gridPattern;
        private IAutomationPattern<IInvokePattern> _invokePattern;
        private IAutomationPattern<IItemContainerPattern> _itemContainerPattern;
        private IAutomationPattern<ILegacyIAccessiblePattern> _legacyIAccessiblePattern;
        ...
        public IFrameworkPatterns Patterns => this;

        IAutomationPattern<IAnnotationPattern> IFrameworkPatterns.Annotation => _annotationPattern ?? (_annotationPattern = InitializeAnnotationPattern());
        IAutomationPattern<IDockPattern> IFrameworkPatterns.Dock => _dockPattern ?? (_dockPattern = InitializeDockPattern());
        IAutomationPattern<IDragPattern> IFrameworkPatterns.Drag => _dragPattern ?? (_dragPattern = InitializeDragPattern());
        IAutomationPattern<IDropTargetPattern> IFrameworkPatterns.DropTarget => _dropTargetPattern ?? (_dropTargetPattern = InitializeDropTargetPattern());
        IAutomationPattern<IExpandCollapsePattern> IFrameworkPatterns.ExpandCollapse => _expandCollapsePattern ?? (_expandCollapsePattern = InitializeExpandCollapsePattern());
        IAutomationPattern<IGridItemPattern> IFrameworkPatterns.GridItem => _gridItemPattern ?? (_gridItemPattern = InitializeGridItemPattern());
        IAutomationPattern<IGridPattern> IFrameworkPatterns.Grid => _gridPattern ?? (_gridPattern = InitializeGridPattern());
        IAutomationPattern<IInvokePattern> IFrameworkPatterns.Invoke => _invokePattern ?? (_invokePattern = InitializeInvokePattern());
        IAutomationPattern<IItemContainerPattern> IFrameworkPatterns.ItemContainer => _itemContainerPattern ?? (_itemContainerPattern = InitializeItemContainerPattern());
        IAutomationPattern<ILegacyIAccessiblePattern> IFrameworkPatterns.LegacyIAccessible => _legacyIAccessiblePattern ?? (_legacyIAccessiblePattern = InitializeLegacyIAccessiblePattern());
        ...
    }
}

如果按下面的方式更改调用，则没有错误，但树项没有展开，

((FrameworkAutomationElementBase.IFrameworkPatterns)(my_legacy_tree_item.Patterns)).LegacyIAccessible.Pattern.DoDefaultAction()

试图使用下面的强制转换抛出错误，

((FrameworkAutomationElementBase.IFrameworkPatterns[ILegacyIAccessiblePattern])(parent.Patterns)).LegacyIAccessible.Pattern.DoDefaultAction()

Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object.
   at Python.Runtime.GenericUtil.GenericByName(String ns, String name, Int32 paramCount)
   at Python.Runtime.ClassBase.type_subscript(IntPtr idx)

Answer 1

回答我自己的问题，因为这是一个愚蠢的错误。

下面的行实际上扩展了遗留树项，

((FrameworkAutomationElementBase.IFrameworkPatterns)(my_legacy_tree_item.Patterns)).LegacyIAccessible.Pattern.DoDefaultAction()

但是，由于在我的示例中，我也立即右键单击了同一项，在树项展开之前会弹出上下文菜单。因此，在上述调用之后添加sleep(1)对我来说是有效的。

另外，my_legacy_tree_item.DoubleClick()和sleep(1)也起作用。