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title, type, order
| title | type | order |
|---|---|---|
| Chapter 10 Outlook: Introduction of C++20 | book-en-us | 10 |
Chapter 10 Outlook: Introduction of C++20
[TOC]
C++20 seems to be an exciting update.
For example, as early as C++11, the Concept,
which was eager to call for high-altitude but ultimately lost, is now on the line.
The C++ Organizing Committee decided to vote to finalize C++20 with many proposals,
such as Concepts/Module/Coroutine/Ranges/ and so on.
In this chapter, we'll take a look at some of the important features that
C++20 will introduce.
Concept
The concept is a further enhancement to C++ template programming. In simple terms, the concept is a compile-time feature. It allows the compiler to evaluate template parameters at compile-time, greatly enhancing our experience with template programming in C++. When programming with templates, we often encounter a variety of heinous errors. This is because we have so far been unable to check and limit template parameters. For example, the following two lines of code can cause a lot of almost unreadable compilation errors:
#include <list>
#include <algorithm>
int main() {
std::list<int> l = {1, 2, 3};
std::sort(l.begin(), l.end());
return 0;
}
The root cause of this code error is that std::sort must provide
a random iterator for the sorting container, otherwise it will not be used,
and we know that std::list does not support random access.
In the conceptual language, the iterator in std::list does not satisfy
the constraint of the concept of random iterators in std::sort.
After introducing the concept, we can constrain the template parameters
like this:
template <typename T>
requires Sortable<T> // Sortable is a concept
void sort(T& c);
abbreviate as:
template<Sortable T> // T is a Sortable typename
void sort(T& c)
Even use it directly as a type:
void sort(Sortable& c); // c is a Sortable type object
Let's look at a practical example.
TODO:
Module
TODO:
Contract
TODO:
Range
TODO:
Coroutine
TODO:
Conclusion
In general, I finally saw the exciting features of Concepts/Ranges/Modules in C++20. This is still full of charm for a programming language that is already in its thirties.
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Licenses
This work was written by Ou Changkun and licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. The code of this repository is open sourced under the MIT license.