Sample for IDynamicInterfaceCastable

[elinor-fung]

Summary

Add a sample using the new IDynamicInterfaceCastable API.

cc @AaronRobinsonMSFT @jkoritzinsky

[jkotas]

The function pointers are shipping in previews already. Can the sample be modified to use them?

[elinor-fung]

The new syntax for specifying the calling convention (e.g. cdecl -> unmanaged[Cdecl]) isn't in the shipped previews yet. I was planning on updating the sample once they can use the new syntax.

[elinor-fung]

@dotnet/docs This sample involves building a native library. To make it a bit simpler for users to run, it hooks the native build in such that dotnet run and dotnet build will build the native library. This is the same system as that used for the marshaling and hosting samples. The prerequisite to make this work is the have the C++ compiler for the platform be installed and on the path when building. The CI build is failing because the C++ compiler is not found - is there a recommendation for what we should do here? Maybe have the CI set some property such that the projects could conditionally skip doing the native build?

[IEvangelist]

I have some nits for the C# bits, otherwise this is looking awesome!

[IEvangelist]

This actually needs a README.md with metadata, so that it is indexed by the samples browser.

Here is an example:
https://github.com/dotnet/samples/blob/master/async/async-and-await/cs/readme.md

[IEvangelist]

Needs a README.md

[adegeo]

@dotnet/docs This sample involves building a native library. To make it a bit simpler for users to run, it hooks the native build in such that dotnet run and dotnet build will build the native library. This is the same system as that used for the marshaling and hosting samples. The prerequisite to make this work is the have the C++ compiler for the platform be installed and on the path when building. The CI build is failing because the C++ compiler is not found - is there a recommendation for what we should do here? Maybe have the CI set some property such that the projects could conditionally skip doing the native build?

I would love to get CI working for this. I checked on my computer that has the latest VS2019 preview and I don't have the following according to the readme:

• Using Developer Command Prompt for VS 2019 Int Preview, cl.exe doesn't resolve to anything.
• There is no x64 Native Tools Command Prompt for VS 2019 shortcut on my machine.

[elinor-fung]

This actually needs a README.md with metadata, so that it is indexed by the samples browser.

Nice - I had no idea that was a thing. Will update.

There is no x64 Native Tools Command Prompt for VS 2019 shortcut on my machine.

Do you have a C++ workload installed for VS? I'll make the readme point out
https://docs.microsoft.com/cpp/build/building-on-the-command-line#download-and-install-the-tools.

The CI is only on Windows currently, right?

[adegeo]

Do you have a C++ workload installed for VS? I'll make the readme point out
https://docs.microsoft.com/cpp/build/building-on-the-command-line#download-and-install-the-tools.

The CI is only on Windows currently, right?

Ahh that is probably the reason. I believe the CI machine has all workloads installed, so the command would work there. CI is only on Windows yes. Tomorrow I'll work on getting Preview 7 installed and the CI to use dotnet via the developer command prompt. It currently only runs it directly.

[elinor-fung]

@adegeo I updated the sample so that it should automatically find the MSVC compiler based on the bitness of the dotnet executable doing the build. It works locally for me. With that, hopefully moving Preview 7 is all that is needed for the CI.

[adegeo]

Awesome! CI passed!

[elinor-fung]

@IEvangelist I have updated the README to include metadata for indexing by the samples browser. Do you have any additional concerns with this?

[elinor-fung]

@adegeo Seems like the CI is now expecting the added global.json to correspond a project in its current directory or a parent directory, but not finding one?

Running "LocateProjects "d:\a\samples\samples" --pullrequest 3744 --owner dotnet --repo samples"
1|core/interop/IDynamicInterfaceCastable/global.json|

When it was passing before, global.json wasn't listed by LocateProjects.

[IEvangelist]

Looks good to me, we'll - thank you 🙏