I’ve been spending some time looking at how to wrap some of our existing C API that is based on completion callbacks, with C++ coroutines. I just got it working tonight and I thought I’d document what I’ve learned in this process and hopefully help other folks. My focus is the stackless coroutine / resumable functions proposed by Gor Nishanov et al and it is supported by Microsoft VC++ and Clang. I won’t be talking about boost::coroutine. I also won’t be talking about how to use coroutines - this is about how to write your own light-weight coroutine plumbing for library authors.
If you come from a C++ programming background, you are most likely already familiar with C++’s template code bloat problem. Each template instantiation gets its own copy of the code (of course, compiler/linker can optimize by throwing away unused methods). The reason being that C++ template are more like C macro on steriods. I know this is a great simplification, but at the end of the day, it is pretty much a code expansion feature with type safety. This grants C++ some powerful capabilities that C# developers don’t have - like template specialization, or calling arbitary methods on a template class, or a whole different programming paradigm that’s known as template meta-programming. On the other hand, .NET generics require you to define what operations can be perform on T using constraints (otherwise you are limited to a small set of operations such as casts, assignments, etc). However, this does give .NET a unique advantage - it can do a better job at code sharing.
I recently had some really interesting discussion with a .NET typesystem expert in the team, and during the conversation he had pointed out an interesting aspect of .NET value type boxing when using constraints. Intrigued by that discussion, I decided to take a further look.
If you’ve been following .NET Core development you’ve probably already heard about .NET Standard 2.0. We are bringing back a lot of APIs from desktop to .NET Core to make migrating existing apps easier. If you’d like to read more about what is netstandard, you can refer to this faq. In this post I’m going to show you how to dogfood (read: try out the bleeding edge new stuff) the latest .NET Core 2.0 which has the latest API changes in .NET Standard 2.0.
I’ve spent a non-trival part of my career adding Windows Runtime support to .NET framework and .NET native, and I often get people asking me what is Windows Runtime and there is a lot of confusion around it. The bad naming certainly doesn’t help in this case. I’m going to write a series blog post so that I can point people to. :)