spencersharp2010 / c-17-new-features

Showcases some new features associated with C++17

C++17 New Features

Some brief code I wrote to showcase a few new language features of C++17. Specifically, I demonstrated:

• if constexpr
• constexpr lambda functions
• capturing *this in lambda functions

Note: you must compile with either -std=c++17 or -std=c++2a compiler flag with g++.

if constexpr

This allows for compile-time evaluation of an if statement. It is typically used in conjunction with templates and some Boolean operator. The unused branch of the if statement is discarded, meaning it does not have to be able to compile.

It is similar to std::enable_if but much cleaner.

constexpr lambdas

Functions could be declared constexpr since C++11 but not lambda functions. In C++17, lambdas are implicitly constexpr when all conditions are satisfied. This allows lambda functions to be evaluated at compile time. One can also explicitly declare a lambda as constexpr.

Capturing *this in lambda functions

Lambda functions can be used within a class to access member variables of that class, but must explicitly capture this.

Until C++14, one could only capture by reference. C++17 introduced a solution for cleanly capturing *this by value.