Question

I think everyone has experience working with a code like the following:

void fun(Type1&);
void fun(Type2&);
vector<Type1> vec;
for_each(vec.begin(), vec.end(), fun);

Of course that won’t compile, because it’s not clear which function to be passed. And what’s your commonly-used solution to the problem?

I know this will work:

for_each(vec.begin(), vec.end(), (void(*)(Type1&))fun);

But any better ideas?

Answer 1

One solution is to use template function:

template<typename T>
void fun(T&);
// specialize fun for Type1 and Type2
...
for_each(vec.begin(), vec.end(), fun<Type1>);

The better way is to use functor with template operator():

struct fun
{
  template<typename T>
  void operator()(T&) const;
};
...
for_each(vec.begin(), vec.end(), fun()); // T for operator() will be deduced automatically