Is There Anything Like a Templatized Case-Statement

Question

So I have this really ugly code:

template 
std::conditional_t

        

Answer 1

I had to do something like this once so I wrote a small wrapper to acheive the result neatly. You could use it as follows (see here for a test)

template
typename static_switch
            ,static_case
            ,static_case
            >::type foo(T bar){ ... }

Behind the scenes it pretty much does what you already have but by wrapping it we keep it (more) readable. There is also a version to allow you to switch direclty on the type T if you needed that.

Edit: At @Deduplicator's suggestion here is the code behind it

#include   

/* 
 * Select a type based on the value of a compile-time constant such as a 
 * constexpr or #define using static_switch. 
 */ 

template 
struct static_case { 
    static constexpr int value = I; 
    using type = T; 
}; 

template 
struct static_switch{ 
    using type = typename std::conditional< I==Case1::value ,  
                    typename Case1::type, 
                    typename static_switch::type 
                     >::type; 
}; 

struct fail_on_default {};

template 
struct static_switch { 
    using type = typename std::conditional< I==LastCase::value ,  
                    typename LastCase::type, 
                    DefaultType 
                     >::type; 

    static_assert(!(std::is_same::value),
                  "Default case reached in static_switch!");
};