C++ OOP: Template Specialization, Inheritance, and Resolution Order, Slides of Object Oriented Programming

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Object-Oriented Programming

(OOP)

Lecture No. 37

Resolution Order

template< typename T > class Vector { … };

template< typename T > class Vector< T* > { … };

template< > class Vector< char* > { … };

…Example – Resolution Order

int main() { Vector< char* > strVector; // Vector< char* > instantiated

Vector< int* > iPtrVector; // Vector< T* > instantiated

Vector< int > intVector; // Vector< T > instantiated return 0; }

Function Template Overloading

template< typename T > void sort( T );

template< typename T > void sort( Vector< T > & );

template< > void sort< Vector<char> >( Vector< char > & );

void sort( char* );

Example – Resolution Order

int main() { char* str = “Hello World!”; sort(str); // sort( char* )

Vector<char> v1 = {“ab”, “cd”, … }; sort(v1); //sort( Vector<char> & )

…Example – Resolution Order

Vector v2 = { 5, 10, 15, 20 }; sort(v2); // sort( Vector &)

int iArray[] = { 5, 2, 6 , 70 }; sort(iArray); // sort( T )

return 0; }

Derivations of a Template

• A class template may inherit from another

class template

template< class T > class A { … };

template< class T > class B : public A< T > { … };

…Derivations of a Template

int main() { A< int > obj1; B< int > obj2; return 0; }

…Derivations of a Template

int main() { A< int > obj1; B< int* > obj2; return 0; }

…Derivations of a Template

• Complete specialization or ordinary class

cannot inherit from a class template

template< > class B< char* > : public A< T > { … }; // Error: ‘T’ undefined

class B : public A< T > { … }; // Error: ‘T’ undefined

…Derivations of a Partial Sp.

template< class T > class B : public A< T* > { … }

int main() { A< int* > obj1; B< int > obj2; return 0; }

…Derivations of a Partial Sp.

• A partial specialization may inherit from a

partial specialization

template< class T > class B< T* > : public A< T* > { … };

…Derivations of a Partial Sp.

• Complete specialization or ordinary class

cannot inherit from a partial specialization

template< > class B< int* > : public A< T* > { … } // Error: Undefined ‘T’

class B : public A< T* > { … } // Error: Undefined ‘T’

Derivations of a Complete Sp.

• A class template may inherit from a

complete specialization

template< class T > class A { … };

template< > class A< float* > { … };