Better way to say x == Foo::A || x == Foo::B || x == Foo::C || …?

Question

Let\'s say I have a bunch of well-known values, like this (but const char * is just an example, it could be more complicated):

const char *A = \"A\"         


        

Answer 1

You could factor your current best solution into a template:

template
inline bool is_in(const A &a, B (&bs)[n]) {
  return std::find(bs, bs + n, a) != bs + n;
}

which you can use like

X items[] = { A, C, E, G };
if (is_in(some_complicated_expression_with_ugly_return_type, items))
  …