Question

Example routine:

const Armature* SceneFile::findArmature(const Str& name){
    for (int i = 0; i < (int)armatures.size(); i++)
        if (name == armatures[i].name)
            return &armatures[i];
    return 0;
}

Routine’s purpose is (obviously) to find a value within an array of elements, based on element’s member variable, where comparing member variable with external “key” is search criteria.

One way to do it is to iterate through array in loop. Another is to use some kind of “map” class (std::map, some kind of vector sorted values + binarySearch, etc, etc). It is also possible to make a class for std::find or for std::for_each and use it to “wrap” the iteration loop.

What are other ways to do that?

I’m looking for alternative ways/techniques to extract the required element.
Ideally – I’m looking for a language construct, or a template “combo”, or a programming pattern I don’t know of that would collapse entire loop or entire function into one statement. Preferably using standard C++/STL features (no C++0x, until it becomes a new standard) AND without having to write additional helper classes (i.e. if helper classes exist, they should be generated from existing templates).

I.e. something like std::find where comparison is based on class member variable, and a variable is extracted using standard template function, or if variable (the one compared against “key”(“name”)) in example can be selected as parameter.

The purpose of the question is to discover/find language feature/programming technique I don’t know yet. I suspect that there may be an applicable construct/tempalte/function/technique similar to for_each, and knowing this technique may be useful. Which is the main reason for asking.

Ideas?

Answer 1

If you have access to Boost or another tr1 implementation, you can use bind to do this:

const Armature * SceneFile::findArmature(const char * name) {
  find_if(armatures.begin(), armatures.end(),
    bind(_stricmp, name, bind(&string::c_str, bind(&Armature::name, _1))) == 0);
}

Caveat: I suspect many would admit that this is shorter, but claim it fails on the more elegant/simpler criteria.