Creating a co_await awaitable signal that can be awaited multiple times, part 3

by Raymond Chen

Last time, we created an awaitable signal that can be awaited multiple times, but noted that it took kernel transitions a lot. Let’s implement the entire thing in user mode...

“Professional C++, 5th Edition” Released

by Marc Gregoire

After working on it for a year, I’m proud to announce my new book “Professional C++, 5th Edition” is finished ��

It has been updated to the C++20 standard and uses certain C++20 features, such as modules and std::format(), throughout all examples...

Creating a co_await awaitable signal that can be awaited multiple times, part 2

by Raymond Chen

Last time, we created an awaitable signal that can be awaited multiple times. We noted that one problem with the implementation is that the object couldn’t be copied: Everybody has to await the same object, which can create lifetime issues...

Online C++ User Group Meetings in March 2021

by Jens Weller

The monthly overview of upcoming User Group meetings, still online meetups due to the pandemic.

On March 16th Meeting C++ hosts the second online C++ job fair, RSVP via meetup!

Implementing Simple Futures with Coroutines

by Rainer Grimm

Instead of return, a coroutine uses co_return returning its result. In this post, I want to implement a simple coroutine using co_return...

return first example

by Marius Elvert

It seems my “return first” post was not as enlightening as I had hoped. It was posted on reddit, and while the majority of commenters completely missed the point, it wasn’t really clear for those that did not just read the title. Either way, I am to blame for that – the examples and my reasoning were not very conclusive. So let me try clearing up the confusion with a better example...

Creating a co_await awaitable signal that can be awaited multiple times, part 1

by Raymond Chen

C++/WinRT asynchronous activities can be awaited only once. This is consistent with their intended usage pattern, which is for an application to start the activity, co_await the result, and then continue.

But maybe you want something like a Win32 event, where any number of people can co_await the event, and then once it is signaled, all the awaiters are resumed...

C++ Concepts: More than Syntactic Requirements

by Jonathan Boccara

After years and years of expectation, concepts have finally made it in C++20.

Concepts are descriptions in code of a set of expressions that must be valid with a given type. Those are syntactic requirements. But there is more to concepts than that: concepts also have semantic requirements.

Before getting into that, here is a recap of what concepts are. If you’re already familiar with concepts you can skip to the section on semantic requirements...

My tutorial and take on C++20 coroutines

by David Mazières

Over the last 25 years, I’ve written a lot of event-driven code in C++. A typical example of event-driven code is registering a callback that gets invoked every time a socket has data to be read. Once you have read an entire message, possibly after many invocations, you parse the message and invoke another callback from a higher layer of abstraction, and so forth. This kind of code is painful to write because you have to break your code up into a bunch of different functions that, because they are different functions, don’t share local variables...

Synchronized Output Streams with C++20

by Rainer Grimm

What happens when you write without synchronization to std::cout? You get a mess. With C++20, this should not be anymore...