intermediate

Ranges, Coroutines, and React: Early Musings on the Future of Async in C++—Eric Niebler

Eric Niebler shares his thoughts about the interaction of ranges and co-routines in his recent blog post.

Ranges, Coroutines, and React: Early Musings on the Future of Async in C++

by Eric Niebler

From the article:

Another way to look at this is that synchronous ranges are an example of a pull-based interface: the user extracts elements from the range and processes them one at a time. Asynchronous ranges, on the other hand, represent more of a push-based model: things happen when data shows up, whenever that may be. This is akin to the reactive style of programming.

By using ranges and coroutines together, we unify push and pull based idioms into a consistent, functional style of programming. And that’s going to be important, I think.

Quick Q: Make C++ fail compilation on specific instantiation of template function

Quick Q: Delete its constructor

Recently on SO:

Make C++ fail compilation on specific instantiation of template function

Since foo is a complete specialization, it will always get compiled, and the static assert will always get called.

However, there’s an easier way:

template <>
Bar foo<Bar>(Bar val) = delete;

This will say that this specific version is deleted, and cannot be called.

Your own error condition—Andrzej Krzemieński

The series continues.

Your own error condition

by Andrzej Krzemieński

From the article:

In the previous post we have seen how you can create your own error-code enumeration for representing different reasons for failure in your component, and how you can store them and convey them type erased via std::error_code. In this post we will see how you can inspect an error situation encoded in std::error_code, and how you can build useful queries about error conditions.

Quick Q: Why are static addresses constexpr?

Quick A: Because it is defined at compile time in a special section.

Recently on SO:

A little confused about constexpr functions

If 'x' is declared static, there are no errors. Why?

This is because there is always exactly one x in the program. It has an address (somewhere in the .data segment under normal conditions).

Confusingly, both static and extern keywords specify the storage duration as static (they differ in linkage)

How is it possible to get a variable address during the compilation process? Aren't they allocated at run-time?
Variables with automatic, dynamic or thread storage durations are allocated at runtime. Static duration variables are allocated by the compiler. (The linker and OS can change the location, but they know how to fix all the references when they do)

 

The reviews at r/cpp_review have begun!

Participate in the first two reviews at r/cpp_review:

The reviews have begun

by Jens Weller

From the article

A few weeks ago I announced a C++ review community, which since then has grown to 250+ members on reddit. There has been great feedback and discussions since then, so that the idea is now ready to be tested.  With August, the first review period has started

(Not Really So) New Niche for C++: Browser!?—No Bugs Hare

In this article "No Bugs" Hare outlines the possibility to run C++ code in the major four web browsers.

(Not Really So) New Niche for C++: Browser!?

by "No Bugs" Hare

From the article:

For quite a long while, C++ had been losing popularity; for example, as reported in [Widman16], in 2016 it got 7% less of the listings on Dice.com compared with a year earlier; and according to [TIOBE17], from the C++ Golden Age in 2004 till 2017, the C++ share fell from ~17% to a measly 6%.

As all of us (as in, ‘hardcore C++ fans’) know , this has nothing to do with the deficiencies of C++; rather it is related to an observation that the time of downloadable clients (which was one of the main C++ strongholds) has changed into the time of browser-based clients – and all the attempts to get C++ onto browsers were sooo ugly (ActiveX, anyone?) that this didn’t really leave a chance to use C++ there.

Well, it seems that this tendency is already in the process of being reverted:

C++ can already run on all four major browsers – and moreover, it has several all-important advantages over JavaScript, too.
And this – not too surprisingly – is what this article is all about.

C++17 attributes - maybe_unused, fallthrough and nodiscard—Simon Brand

Do you know these new attributes?

C++17 attributes - maybe_unused, fallthrough and nodiscard

by Simon Brand

From the article:

C++17 adds three new attributes for programmers to better express their intent to the compiler and readers of the code: maybe_unused, fallthrough, and nodiscard. This is a quick post to outline what they do and why they are useful.