Computer Notes - Resolution Order

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Resolution Order
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Resolution Order

• templatelt typename T gt
• class Vector
• templatelt typename T gt
• class Vectorlt T gt
• templatelt gt
• class Vectorlt char gt

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3
Resolution Order

• Compiler searches a complete specialization whose
  type matches exactly with that of declaration
• If it fails then it searches for some partial
  specialization
• In the end it searches for some general template

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Example Resolution Order

• int main()
• Vectorlt char gt strVector
• // Vectorlt char gt instantiated
• Vectorlt int gt iPtrVector
• // Vectorlt T gt instantiated
• Vectorlt int gt intVector
• // Vectorlt T gt instantiated
• return 0

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5
Function Template Overloading

• templatelt typename T gt
• void sort( T )
• templatelt typename T gt
• void sort( Vectorlt T gt )
• templatelt gt
• void sortlt Vectorltchargt gt(
• Vectorlt char gt )
• void sort( char )

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Resolution Order

• Compiler searches target of a function call in
  the following order
• Ordinary Function
• Complete Specialization
• Partial Specialization
• Generic Template

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Example Resolution Order

• int main()
• char str Hello World!
• sort(str) // sort( char )
• Vectorltchargt v1 ab, cd,
• sort(v1) //sort( Vectorltchargt )

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Example Resolution Order

• Vectorltintgt v2 5, 10, 15, 20
• sort(v2) // sort( VectorltTgt )
• int iArray 5, 2, 6 , 70
• sort(iArray) // sort( T )
• return 0

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9
Templates and Inheritance

• We can use inheritance comfortably with templates
  or their specializations
• But we must follow one rule
• Derived class must take at least as many
  template parameters as the base class requires
  for an instantiation

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Derivations of a Template

• A class template may inherit from another class
  template
• templatelt class T gt
• class A
• templatelt class T gt
• class B public Alt T gt

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Derivations of a Template

• int main()
• Alt int gt obj1
• Blt int gt obj2
• return 0

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Derivations of a Template

• A partial specialization may inherit from a class
  template
• templatelt class T gt
• class Blt T gt public Alt T gt

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Derivations of a Template

• int main()
• Alt int gt obj1
• Blt int gt obj2
• return 0

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Derivations of a Template

• Complete specialization or ordinary class cannot
  inherit from a class template
• templatelt gt
• class Blt char gt public Alt T gt
• // Error T undefined
• class B public Alt T gt
• // Error T undefined

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Derivations of a Partial Sp.

• A class template may inherit from a partial
  specialization
• templatelt class T gt
• class A
• templatelt class T gt
• class Alt T gt

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Derivations of a Partial Sp.

• templatelt class T gt
• class B public Alt T gt
• int main()
• Alt int gt obj1
• Blt int gt obj2
• return 0

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Derivations of a Partial Sp.

• A partial specialization may inherit from a
  partial specialization
• templatelt class T gt
• class Blt T gt public Alt T gt

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Derivations of a Partial Sp.

• int main()
• Alt int gt obj1
• Blt int gt obj2
• return 0

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Derivations of a Partial Sp.

• Complete specialization or ordinary class cannot
  inherit from a partial specialization
• templatelt gt
• class Blt int gt public Alt T gt
• // Error Undefined T
• class B public Alt T gt
• // Error Undefined T

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20
Derivations of a Complete Sp.

• A class template may inherit from a complete
  specialization
• templatelt class T gt class A
• templatelt gt
• class Alt float gt

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Derivations of a Complete Sp.

• templatelt class T gt
• class B public Alt float gt
• int main()
• Alt float gt obj1
• Blt int gt obj2
• return 0

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Derivations of a Complete Sp.

• A partial specialization may inherit from a
  complete specialization
• templatelt class T gt
• class Blt T gt public Alt float gt

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Derivations of a Complete Sp.

• int main()
• Alt float gt obj1
• Blt int gt obj2
• return 0

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Derivations of a Complete Sp.

• A complete specialization may inherit from a
  complete specialization
• templatelt gt
• class Blt double gt
• public Alt float gt

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Derivations of a Complete Sp.

• int main()
• Alt float gt obj1
• Blt double gt obj2
• return 0

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Derivations of a Complete Sp.

• An ordinary class may inherit from a complete
  specialization
• class B public Alt float gt

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Derivations of a Complete Sp.

• int main()
• Alt float gt obj1
• B obj2
• return 0

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Derivations of Ordinary Class

• A class template may inherit from an ordinary
  class
• class A
• templatelt class T gt
• class B public A

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Derivations of Ordinary Class

• int main()
• A obj1
• Blt int gt obj2
• return 0

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Derivations of Ordinary Class

• A partial specialization may inherit from an
  ordinary class
• templatelt class T gt
• class Blt T gt public A

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31
Derivations of Ordinary Class

• int main()
• A obj1
• Blt int gt obj2
• return 0

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Derivations of Ordinary Class

• A complete specialization may inherit from an
  ordinary class
• templatelt gt
• class Blt char gt public A

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Derivations of Ordinary Class

• int main()
• A obj1
• Blt char gt obj2
• return 0

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