THECODEPROGRAM

Let's Begin

Firstly we need to know a couple of definitions. These definitions are base of usage of template programming.

What is Generic Programming
Generic programming is developing a program as parametric based. It means we can use same class, method or any type of algorithm for different type of data types. For example we can use vectors with integer values and string values. These vectors are designed for generic using purposes.

What is Template Programming
Template programming is a efficient way to write generic blocks. Templates let us to write same code for different type of data types. We can create generic classes and methods in C++. Temlate programming is a way of compile time polymorphism

How Function Templates work in C++

When we write a template method and call it with different type of data types it will be like below:

template <typename T> void TemplateExample::myTemplateFunc(T p1, T p2){
    //...
}

void TemplateExample::perform(){
     this->myTemplateFunc(2.3, 5.6);
     this->myTemplateFunc('a', 'v');
}

void TemplateExample::myTemplateFunc(double p1, double p2){
    //...
}

void TemplateExample::myTemplateFunc(char p1, char p2){
    //...
}

void TemplateExample::perform(){
     this->myTemplateFunc(2.3, 5.6);
     this->myTemplateFunc('a', 'v');
}

As we can see metaprogramming is happening here and our template method is rewriting by compiler for overloading for all used data types .

What is Template Class in C++ ?

template <typename T1, typename T2> class TheClass {

private:
    //Define the variables inside
    T1 key;
    T2 value;

public:

};

TheClass <int, QString> *dict = new TheClass <int, QString>();

IMPORTANT
IN QT YOU CAN NOT USE SIGNAL-SLOT MECHANISM DIRECTLY IN TEMPLATES.

template<typename T1, typename T2> class TheClass  {
    //First we define our variables inside
    T1 p1;
    T2 p2;
public:
    A(T1 p1, T2 p2) { 
             cout<<"Class initialized with parameters : "<< p1 << " and  " << p2 <<endl;  
     }
};

TheClass  <int, int> the1 = new TheClass  <int, int>(22, 33);
TheClass  <QString, int> the2 = new TheClass  <QString, int>("Burak Hamdi TUFAN", 33);
TheClass  <int, QString> the3 = new TheClass  <int, QString>(33, "The Code Program");

Class initialized with parameters : 22 and  33
Class initialized with parameters : Burak Hamdi TUFAN and   33
Class initialized with parameters : 33 and  The Code Program

Now we know how can we declare and use template classes in C++ programming language.

That is all in this article.

Burak Hamdi TUFAN