CODEWITHSUNDEEP
reflectionc++-winrt
Burt_Harris
Burt_Harris

Reputation: 6874

What reflection mechanisms are available in C++/WinRT?

I remember C++ had some runtime type information (RTTI) added sometime after Bjarne Stroustrup's original The C++ Programming Language, but I never had call to use it.

I am familiar with some of the COM and CLR reflection APIs including ITypeInfo and System.Reflection. Would any of these work in against types declared in compiled C++/WinRT app?

This question addressed a similar question 5 years back for C++/CX, have there been changes?

Upvotes: 1

Views: 439

Answers (1)

Ben Kuhn
Ben Kuhn

Reputation: 451

C++ /WinRT doesn't add to the native reflection capabilities of C++. However, the xlang metadata reader APIs can be used to inspect Windows Runtime metadata files (.winmd) that describe WinRT types. You can see the metadata reader library here (and there are examples of usage in the various tools in this repo):

https://github.com/Microsoft/xlang/blob/master/src/library/meta_reader.h

You can use that in conjunction with the Windows function RoGetMetadataFile to locate the metadata for a type at runtime.

https://learn.microsoft.com/en-us/windows/desktop/api/rometadataresolution/nf-rometadataresolution-rogetmetadatafile

Note that C++ /WinRT itself does not use the winmd file at runtime, and as such, code built with C++ /WinRT does not require the winmd to be available at runtime. If the winmd isn't present, you won't be able to rely on it for type information.

If the metadata file is supplied for a type written in C++ /WinRT, the .NET runtime can use the winmd to reflect over the projected types in much the same way that it can reflect over types written using the .NET runtime.

C++ /WinRT does not provide any support at this time for dynamic invocation of types. This is an infrequent but recurring ask and is on our backlog.

Thanks,

Ben

Upvotes: 3

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