C++20 Coroutines--Martin Bond
A first step.
C++20 Coroutines
by Martin Bond
From the article:
There seems to be a lot of confusion around the implementation of C++20 coroutines, which I think is due to the draft technical specification for C++20 stating that coroutines are a work in progress so we can’t expect full compiler and library support at this point in time.
A lot of the problems probably arise from the lack of official documentation about working with coroutines. We have been given C++ syntax support for coroutines (the co_yield and co_return) but without all of what I consider full library support. The standard library has hooks and basic functionality for supporting coroutines, but we must incorporate this into our own classes. I anticipate that there will be full library support for generator style coroutines in C++23.
The C++20 specification is obviously looking to provide support for parallel (or asynchronous) coroutines using co_await, which makes the implementation of a simpler generator style synchronous coroutines more complex. The implementation requirements for our coroutines utilises a Future and Promise mechanism similar to the std::async mechanism for asynchronous threads.
If you are a Python or C# developer expecting a simple coroutine mechanism, you’ll be disappointed because the C++20 general purpose framework is incomplete. Having said that, there are many blogs and articles on the web that include a template class that supports generator style coroutines. This blog contains a usable coroutine template and example code after discussing what a coroutine is...
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Registration is now open for CppCon 2021, which starts on October 24 and will be held 
Registration is now open for CppCon 2021, which starts on October 24 and will be held