Difference between revisions of "Intermediate C++ Game Programming Tutorial 18"

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* Design choices in class hierarchy: inheritance vs. composition [https://youtu.be/cdOB_gKnJOM?t=0m43s 0:43]
 
* Design choices in class hierarchy: inheritance vs. composition [https://youtu.be/cdOB_gKnJOM?t=0m43s 0:43]
 
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Revision as of 22:21, 13 October 2019

Another two-parter here, and we got the real stuff now. Virtual functions allow you to unlock the true potential of inheritance in C++. You need to know this shit.

Topics Covered

Part 1

  • How to create a virtual function
  • Using the override keyword
  • Creating a pure virtual function
  • Using a container of pointers to manage a heterogeneous collection of objects
  • virtual destructors

Part 2

  • Using inheritance and composition together
  • Basic idea of a polymorphic state machine and its application to entity behavior

Video Timestamp Index

Tutorial 18.1

[Expand]
  • Creating a "Virtual Function" in the MemeFighter class 0:23
  • Enabling "Dynamic Dispatch" by using virtual on the member function in the base class 3:17
  • Applying the override keyword to increase code safety 5:17
  • Making a base class member function "Pure Virtual" using virtual void Func(...) = 0; 7:08
  • We have now applied the concept of "Polymorphism" 9:16
  • Applying Polymorphism to a container of pointers to the shared base type of different derived class objects 9:46
  • Applying Polymorphism to objects created on the heap (dynamic memory management) 13:46
  • "Virtual Destructors": Managing destructors in base and derived classes 14:48
  • Review of termonology and concepts learned 19:49

Tutorial 18.2

[Expand]
  • Design choices in class hierarchy: inheritance vs. composition 0:43
  • Adjusting the MemeFighter code to include the Weapon class 4:20
  • Add feature where one fighter can take the other fighter's weapon 11:36
  • Recap of advantage of the inheritance-composition construct 14:00
  • One more real world example 14:28
  • WORK-IN-PROGRESS

Source Code

Inheritance Github Repository

Errata

  • Forgot the virtual destructor for class Weapon! (this one hurts)
  • In the children, the function signatures should be: int CalculateDamage( const Attributes& attr,Dice& d ) const override
  • Though not technically an error, it might have been a better decision to make Weapon::GetName() and Weapon::GetRank() (pure) virtual functions (this would reduce the amount of per-instance data to just the vtable ptr)

See also