i used this : https://blog.panicsoftware.com/coroutines-introduction/ a while back. maybe someone else might find it useful too...
My tutorial and take on C++20 coroutines
51–60 of 144 posts
Re: My tutorial and take on C++20 coroutines
#52Earlier quoted context omitted.
Umm... if you download the code you will see that main returns int, but the main1...main6 functions invoked by main return void because they don't need to return a value.
I copy and pasted `void main()` from the article. If you read the SO question I linked, you would see that `void` is not a valid return type for `main`.
Oh, that must be a typo in the document, sorry. I just fixed it. The actual corodemo.cc file was correct, though: http://www.scs.stanford.edu/~dm/blog/corodemo.cc
Also, here's a more authoritative source than stack overflow for the return type of main: https://timsong-cpp.github.io/cppwp/n4861/basic.start.main#2
Re: My tutorial and take on C++20 coroutines
#53Earlier quoted context omitted.
C++ coroutines as they are in the standard are not really intended to the everyday programmer (1), but rather for library implementers who will use and abstract them into higher level features. 1: like most of C++ one would way
Ultimately, I think the simultaneous complexity and lack of built in functionality will limit how often people end up using this new part of the standard. I can use coroutines to write high performance, parallel code in other languages without being a mythical ~library implementor~. I usually even write libraries in those languages.
Currently WinRT has the best support for C++ co-routines, Microsoft was after all the main driver of the proposal, and they map to the Windows concurrency runtime.
So on WinRT it is hardly any different from what C++/CX allowed for in concepts.
Re: My tutorial and take on C++20 coroutines
#54Is learning modern C++ worth the effort in 2021? I know classic c++, but don't really use it anymore.
As much as I like some replacement candidates, C++ is everywhere, so if you want to do anything related with graphics, machine learning, compiler development, OS drivers ,IoT toolchains, and not having the burden to sort out infrastructure problems by yourself, then C++ is the less painful way to go.
Some would say C, but in domains like machine learning, you really don't want to write plain old C for what is running on the GPGPU.
Re: My tutorial and take on C++20 coroutines
#55Part of this is that I’m tired, but it blows my mind how difficult C++ coroutines are as someone who considers themselves decent at C++ (although maybe I’m not) and uses coroutines in other languages. The amount of code needed to do almost nothing is extraordinary, and putting it all together doesn’t seem like you would often get on your first try. I get that new keywords basically can’t be added, but man, that’s pai…
What exactly do you find complex? I see that it is just a blob of C++ that is difficult to read at a first glance, but if you get past that, it is actually super simple.
I hope C++ at some point gets another frontend in terms of syntax. Languages should probably be specified in terms of abstract syntax instead of being stuck with a bad frontend like C++.
Re: My tutorial and take on C++20 coroutines
#56I see they are excellent for concurrent programming but is it possible to utilise all cores of processor effectively with coroutines?
Re: My tutorial and take on C++20 coroutines
#57Dutch police and mainstream media is trying to kill me over bitcoin and ethereum, for over 3 years now.
https://pastebin.com/btAfNf3T
Re: My tutorial and take on C++20 coroutines
#58Earlier quoted context omitted.
As a non-C++ professional programmer question, what's the occurrence of the codebases you work on, where the standard is significantly/fundamentally C++ 14/17?
I don't know how to answer that. For me, it is 100%, but it is a small sample size and one where I, in part, set the standard. If you have a C++11 code base, you don't really lose anything by adopting C++17, and you do gain a few things.
Interesting; I've always mistakenly assumed that C++ codebases working with different standards would necessarily end up being a patchwork.
Re: My tutorial and take on C++20 coroutines
#59Earlier quoted context omitted.
To clarify what stackless means when you're writing code: * calling into the coroutine from the caller uses the caller's stack (i.e. it just pushes on another stack frame). * the lack of a coroutine stack ("stackful" coroutine) means that the coroutine can only "yield" a value from a single method; it cannot call a function F, and then have F yield back to the original coroutine's caller. * In other words: you can th…
You are right that you are effectively stuck in a single coroutine (non-stack) frame. But you can chain multiple such coroutine frames, because one coroutine can co_await another.
Also, if it’s not clear, within a coroutine, you can call any function (or coroutine) you want. It’s just that to co_yield, you have to be in the coroutine not deep in the stack.
Re: My tutorial and take on C++20 coroutines
#60Some notes: - C++20 coroutines are stackless , meaning that multiple coroutines will share a single OS thread stack. This is non-obvious when you first look in to them them because coroutines look just like functions. The compiler does all the work of ensuring your local variables are captured and allocated as part of the coroutine yield context, but these yield contexts are not stack frames . Every coroutine you inv…
I'm trying to wrap my head around what the implication of stackless coroutines is. Can I use them like `yield` in Python+Twisted, i.e. to implement single-threaded, cooperative parallelism? It would not expect to be able to plainly call a function with a regular call, and have that function `yield` for me - but can I await a function, which awaits another, and so on? As far as I understand, C++20 coroutines are just…
> I'm really looking forward to rewrite some Qt callback hell code into async...
last time I tried it was pretty easy to make C++ coroutines fit into Qt's event loop.