template-meta-programming

问题 I have difficulties to understand how the following template definition and template specialization definition work? To me, factorial<34> or factorial<T-1> look strange! For example: factorial<T - 1>::value means what? #include <iostream> template<int T> struct factorial { enum { value = factorial<T - 1>::value * T }; }; template<> struct factorial<1> { enum { value = 1 }; }; int main() { std::cout << factorial<34>::value << std::endl; } g++ -o testSTL01 testSTL01.cpp -Wall testSTL01.cpp: In

问题 I'm thinking about a function with signature template<typename ...Ts> std::vector<std::tuple<Ts...>> join_vectors(std::vector<Ts>&&...) { //... }; but probably a more general one accepting any iterable instead of just std::vector would be good. Probably it would have a signature like this? template<template<typename> typename C, typename ...Ts> C<std::tuple<Ts...>> join_vectors(C<Ts>&&...) { // ... }; However, I'm not at this level yet in C++ (despite doing the same in Haskell would be

问题 I am currently writing an interface class that should provide access to to internal elements of a complex structure as const or non-const references. The idea is that some modules are granted const access and some modules are granted full access. I have used the 'type_traits' 'std::add_const' to conditionally qualify the return type of the internal member functions, unfortunately I cannot think of a way of conditionally qualifiying the member functions as const or non-const. Is this even

问题 I am currently writing an interface class that should provide access to to internal elements of a complex structure as const or non-const references. The idea is that some modules are granted const access and some modules are granted full access. I have used the 'type_traits' 'std::add_const' to conditionally qualify the return type of the internal member functions, unfortunately I cannot think of a way of conditionally qualifiying the member functions as const or non-const. Is this even

问题 The following code attempts to partially specialize a class using a concept and add a method to the specialization, but it is rejected by clang 11.0.0: #include <concepts> template <typename T> // note: previous template declaration is here struct S {}; template <std::integral T> struct S<T> { void f(); }; template <std::integral T> // error: type constraint differs in template redeclaration void S<T>::f() { } clang gives the error message: <source>:14:16: error: type constraint differs in

来源： https://stackoverflow.com/questions/64118868/base-case-specialization-for-recursive-variadic-template

来源： https://stackoverflow.com/questions/64139547/how-to-detect-whether-there-is-a-specific-private-member-variable-in-class

来源： https://stackoverflow.com/questions/55288555/c-check-if-statement-can-be-evaluated-constexpr

来源： https://stackoverflow.com/questions/55288555/c-check-if-statement-can-be-evaluated-constexpr

来源： https://stackoverflow.com/questions/34283919/understanding-how-the-function-traits-template-works-in-particular-what-is-the