constexpr with string operations workaround?
c++, c++11, constexpr, stdstring
Solution
Compile-time "string" concatenation :
#include <iostream>
#include <string>
template <char ... CTail>
struct MetaString
{
static std::string string()
{
return std::string{CTail...};
}
};
template <class L, class R>
struct Concatenate;
template <char ... LC, char ... RC>
struct Concatenate<MetaString<LC ... >, MetaString<RC ... >>
{
typedef MetaString<LC ..., RC ... > Result;
};
int main()
{
typedef MetaString<'f', 'o', 'o'> Foo;
typedef MetaString<'b', 'a', 'r'> Bar;
typedef typename Concatenate<Foo, Bar>::Result FooBar;
std::cout << Foo::string() << std::endl; // foo
std::cout << Bar::string() << std::endl; // bar
std::cout << FooBar::string() << std::endl; // foobar
}
Problem
This previously answered question explains why the code I have posted below does not work. I have a follow-up question: is there a workaround that is conceptually equivalent, i.e., achieves compile-time string concatenation, but is implemented in a way that is actually supported by C++11? Using std::string is completely non-essential. ``` constexpr std::string foo() { return std::string("foo"); } constexpr std::string bar() { return std::string("bar"); } constexpr std::string foobar() { return foo() + bar(); } ```