Question

Is it possible to implement this using templates preferably in a way that would work with vectors and arrays, but especially vectors.

• The main functionality, used in PHP as:

  foreach(objects as object)
  { object=this*that; }
  

• It would be nice to have the alternative usage as well if possible:

  foreach(objects as key => object)
  { object=formula(key); }
  

=> is non essential. Templates aside, any technique, would be acceptable given this format.

Answer 1

C++0x supports range-based for:

for (T& object : objects)
   object = this * that;

but not many compilers support this yet (only gcc 4.6 have it AFAIK). Still, you could use std::for_each with a lambda function like:

std::for_each(objects.begin(), objects.end(), [](T& object) {
   object = this * that;
});

 

If you don’t like C++0x, you could use Boost.Foreach like

BOOST_FOREACH(T& object, objects) {
  object = this * that;
}

---

For a std::vector, there is no built-in support for the => form. You need to keep the index yourself.

int key = 0;
for (T& object : objects) {
   object = formula(key);
   ++ key;
}

key = 0;
std::for_each(objects.begin(), objects.end(), [&key](T& object) {
   object = formula(key);
   ++ key;
});