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By Adrien Hamelin | Nov 16, 2020 11:55 AM | Tags: advanced
How do you do it?
Destructing outside the lock when removing items from C++ standard containers
by Raymond Chen
From the article:
Last time, we saw that object destruction is a hidden callout that can cause you to violate the rule against calling out to external code while holding an internal lock...
By Adrien Hamelin | Nov 16, 2020 11:45 AM | Tags: advanced
Quick: in order to make x a dependent name, so that lookup is deferred until the template parameter is known
Recently on SO:
Why do I have to access template base class members through the this pointer?
If the classes below were not templates I could simply have x in the derived class. However, with the code below, I have to use this->x. Why?
template <typename T> class base { protected: int x; }; template <typename T> class derived : public base<T> { public: int f() { return this->x; } }; int main() { derived<int> d; d.f(); return 0; }
By pkeir | Nov 16, 2020 11:05 AM | Tags: None
What next?
C++20 Compile-time Metamath Proof Verification using C'est
by Paul Keir
From the article:
This post introduces C'est, a non-standard version of the C++20 standard library, with enhanced support for compile-time evaluation. The C'est library is also shown applied to the porting of an existing C++ Metamath database verifier for compile-time execution.
By Adrien Hamelin | Nov 9, 2020 12:35 PM | Tags: c++20
Will you use it?
Calendar and Time-Zones in C++20: Calendar Dates
by Rainer Grimm
From the article:
A new type of the chrono extension in C++20 is a calendar date. C++20 offers various ways to create a calendar date and interact with them...
By Daniel G Vergel | Nov 3, 2020 11:19 AM | Tags: c++20
This post revisits the well-known Insertion Sort algorithm as a way to learn and practice several new C++20 features such as concepts, ranges, and projections.
Programming with C++20's Concepts
by Daniel G Vergel
About the article
The article, written in Spanish, follows very closely the way I introduce these topics to my Computer Engineering students at the European University (Madrid, Spain). As previous posts, it tries to mitigate the lack of educational materials on modern C++ currently available in my native language. Code examples are nevertheless self-explanatory and may be of interest to non-Spanish readers as well.
By Adrien Hamelin | Oct 30, 2020 12:47 PM | Tags: c++20
The power of genericity.
C++20 Ranges, Projections, std::invoke and if constexpr
by Bartlomiej Filipek
From the article:
Continuing the topic from last week, let’s dive into the topic of std::invoke. This helper template function helps with uniform syntax call for various callable object types and can greatly reduce the complexity of our generic code...
By Adrien Hamelin | Oct 28, 2020 12:34 PM | Tags: c++20
More concepts.
Semantic requirements in concepts
by Andrzej Krzemieński
From the article:
The word ‘concept’ in the context of C++ generic programming has two meanings. The first is more abstract: it is the notion from the domain of Generic Programming (GP) in general. GP is not tied to any specific language: it is an approach to writing programs, and concepts are part of this approach. In this sense concepts have been with us since the inception of the STL. The second meaning is the keyword concept in C++20 with its associated semantics: its goal is to approximate the more abstract notion of a concept from GP, and this works only to some extent. One notable difference is that concepts in GP specify semantic requirements on types they constrain, and C++ concepts cannot express them directly.
In this post we will see how semantic requirements in concepts can break your program if you don’t pay attention to them, and what can be done in C++20 concepts to account for semantic requirements...
By Adrien Hamelin | Oct 28, 2020 12:01 PM | Tags: intermediate
Did you know?
Tricks with Default Template Arguments
by Jonathan Müller
From the article:
Just like regular function parameters, template parameters can also have default parameters. For class templates, this behaves mostly just like default function arguments: if you pass fewer template arguments than required, default template arguments are used to fill the remaining places. However, for function templates, it gets more complicated as template parameters for functions can be deduced by the normal function arguments. This leads to some interesting side-effects. In particular, default arguments of template parameters don’t need to be put at the end!
Let’s take a look at a couple of things we can do with default template arguments...
By Adrien Hamelin | Oct 28, 2020 11:48 AM | Tags: c++20
More in the standard.
Calendar and Time-Zones in C++20: Time of Day
By Rainer Grimm
From the article:
With C++20, the chrono library from C++11 becomes important additions. The most prominent ones are a calendar and time-zones support. But this is by far not all. C++20 gets new clocks, powerful formatting functionality for time durations, and a time of day type
By Adrien Hamelin | Oct 21, 2020 11:08 AM | Tags: c++17
Did you know about them?
17 Smaller but Handy C++17 Features
by Bartlomiej Filipek
From the article:
When you see an article about new C++ features, most of the time you’ll have a description of major elements. Looking at C++17, there are a lot of posts (including articles from this blog) about structured bindings, filesystem, parallel algorithms, if constexpr, std::optional, std::variant… and other prominent C++17 additions.
But how about some smaller parts? Library or language improvements that didn’t require decades to standardise or violent “battles” at the ISO meetings.
In this article, I’ll show you 17 (plus a few extra!) smaller C++17 things that will improve your code...