Brace Initialisation with Custom Logic

AntiBoilerplate.cpp

// WIP
// For half-baked related ideas in a situation when this won't work or be acceptable, see:
// 
// https://initialiser.godbolt.org/z/esqeYf98W
// https://initialiser.godbolt.org/z/hzqzfsarz
// https://initialiser.godbolt.org/z/a53ojboYd
// https://initialiser.godbolt.org/z/G3nExT9ba
// 

struct Foo {
    static constexpr unsigned ID = 0x33;

    unsigned id;

    const char *a;
    int b;
    float c;

    // For when this would be annoying boilerplate to type
    /*
    
    Foo(const char *a, int b, float c)  
      : id(ID),
        a(a), b(b), c(c)
    {}

    */
    
};

template<class T>constexpr unsigned someBusinessLogic(){
    return T::ID;
}

template<class T> struct Helper : public T{
    template<class... Args> Helper(Args && ... args)
      : T{someBusinessLogic<T>(), args...}
    {}
  // The secret is:
  // - Relying on folding over the arguments
  // - Being able ot put this into the brace-initialisation of the target type
  // - Having a proxy type that can forward 
  //   * (although maybe this can be reworked)
  //   * Without a second type the problem you can have is infinite recursion as the compiler now prefers the template ctor 
  //     over brace-initialisation - which is what enables us to use that syntax aswell below in main.

};


int main(){    

    Helper<Foo> h1("hi", 9, 3.4f),
                h2{"hi", 9, 3.4f}; // Also works using braces.

}