C++/CX exposes `IPropertyValue` through `Platform::Details::CreateValue`, which returns a `Platform::Object` (which just seems to be a `IPropertyValue` object + C++ RTTI) containing the boxed value.
Apps don't seem to call `CreateValue` directly with a typecode. The code for boxing values gets generated when a value type gets assigned to a `Platform::Object` variable, as documented [here.](https://learn.microsoft.com/en-us/cpp/extensions/boxing-cpp-component-extens...) The generated code will:
1. Call `__abi_make_type_id` with a `struct __abi_type_descriptor *` value, which is just a typecode + string pair. This returns a `Platform::Type` object. 2. Call `Platform::Type::GetTypeCode` on the returned `Platform::Type` object to get back the typecode. 3. Call `Platform::Details::CreateValue` with the typecode and a pointer to the actual value that needs to be boxed.
Apart from the usual WinRT methods, `Platform::Type` obejcts also impement the `IEquatable` and `IPrintable` interfaces. I don't know what their vtables look like, though.
The `Platform::Type` and `Platform::Object` classes also have associated RTTI (can be demonstrated by calling `__RTtypeid`), which we'll also need to emit at some point in the future.
-- v3: vccorlib140: Use the correct symbol name for InitControlBlock on i386 and arm. vccorlib140: Implement Platform::Details::CreateValue. vccorlib140: Add stub for Platform::Details::CreateValue. vccorlib140: Implement Platform::Type::{Equals, GetTypeCode, ToString, FullName::get}. vccorlib140: Implement __abi_make_type_id. vccorlib140: Add stub for __abi_make_type_id, Platform::Type{Equals, GetTypeCode, ToString, FullName::get}.