winrt::composing marker struct (C++/WinRT)
A marker type used to indicate to the implements base struct that the type is the outer class of a composable class. This marker type is generated automatically by cppwinrt.exe when necessary, and you should avoid using it manually. For a usage example of marker types, see Marker types.
Syntax
struct winrt::composing
Remarks
If your runtime class derives from another runtime class,
you can call methods on your base class by using the base_type type alias.
Requirements
Minimum supported SDK: Windows SDK version 10.0.17134.0 (Windows 10, version 1803)
Namespace: winrt
Header: %WindowsSdkDir%Include<WindowsTargetPlatformVersion>\cppwinrt\winrt\base.h (included by default)