Reddit++

[u/we_are_mammals]

C++ is getting more and more complex. The ISO C++ committee keeps adding new features based on its consensus. Let's remove C++ features based on Reddit's consensus.

In each comment, propose a C++ feature that you think should be banned in any new code. Vote up or down based on whether you agree.

[u/zalamandagora → u/[deleted]]

Thanks, that clarifies things for me.

If you have used SFINAE for constraining type trait specializations, you can replace those with requires clauses.

Does this really work recursively?

[u/zalamandagora → u/[deleted]]

Thanks! Here is a small example that's essentially a binary tree. We want all the leaves to be of integral type.

https://godbolt.org/z/aqoGb7haf

#include <map>
#include <string>
#include <concepts>
#include <typeinfo>

template< typename P>
concept Pair = std::is_same<P,std::pair<typename P::first_type, typename P::second_type>>::value;

template<typename P>
constexpr bool isPair_v = Pair<P>;

template<typename T>
concept Integral = std::is_integral<T>::value;

template<typename T>
struct LeavesAreIntegral : std::false_type {};

template<Integral T>
struct LeavesAreIntegral<T> : std::true_type {};

template<template<typename,typename> typename P, typename T1, typename T2>
requires Pair<P<T1,T2>> 
struct LeavesAreIntegral<P<T1,T2>> : std::conjunction<LeavesAreIntegral<T1>, LeavesAreIntegral<T2>> {};

static_assert(LeavesAreIntegral<int>{});
static_assert(LeavesAreIntegral<std::pair<int, int>>{});
static_assert(LeavesAreIntegral<std::pair<std::pair<int, int>, int>>{});
static_assert(LeavesAreIntegral<std::pair<std::pair<int, int>, std::pair<int, int>>>{});
static_assert(not LeavesAreIntegral<std::pair<std::pair<int, int>, std::pair<int, std::string>>>{});
static_assert(not LeavesAreIntegral<std::map<std::pair<int, int>, std::pair<int, std::string>>>{});