Understanding C++ Templates, (class, member function and this)

 

template<int INT>

void AAA() {

std::cout << "INT = " << INT << std::endl;

}

How to Call It:

Normal Context (Outside Class):

AAA<2>(); // ✅ Just call directly

AAA<5>(); // ✅ Works fine

AAA<10>(); // ✅ No problem

Inside Template Class Context:

template<typename T>

class MyClass {

template<int INT>

void AAA() {

std::cout << "INT = " << INT << std::endl;

}

void some_function() {

// WRONG:

template AAA<2>(); // ❌ ERROR! Invalid syntax

// CORRECT:

this->template AAA<2>(); // ✅ Works!

AAA<2>(); // ✅ Usually works too

}

};

Key Point:

- template AAA<2>(); is INVALID C++ syntax

- this->template AAA<2>(); is VALID C++ syntax

The Rule:

- template keyword only goes after -> or . in template contexts

- You cannot start a statement with just template

Correct Examples:

this->template AAA<2>(); // ✅ In class context

obj.template AAA<2>(); // ✅ With object

ptr->template AAA<2>(); // ✅ With pointer

AAA<2>(); // ✅ Direct call (no template keyword needed)