Question

I know the point of templates is to generalize your code, however I would like one specific member function of that class to react differently based on what type of object was created.
Specifically I created a Class Dictionary that is meant to be used to create DictionaryNoun or DictionaryAdjective objects. I have a Dictionary::print() that I want to have a code structure as follows:

Dictionary::print(){
   if(this is a Dictionary<Noun> object){
       // Print my nouns in some special way
   }
   if(this is a Dictionary<Adjective> object){
       // Print my adjectives in some special way
   }
   else{ //Print objects in default way}
}

My question is how do I do the type check on my objects?

Answer 1

C++ lets you specialize member functions for specific template arguments. For example, if you have something like this:

template <typename T> class Dictionary {
    /* ... */
};

Then you can specialize what print does for a Dictionary<Noun> by writing

template <>
    void Dictionary<Noun>::print() {
    /* ... special code for printing nouns ... */
}

You can specialize for Adjective the same way. Finally, you can write a default implementation that’s used if neither matches by writing

template <typename T>
    void Dictionary<T>::print() {
    /* ... catch-all code ... */
}

Hope this helps!