Difference between revisions of "Intermediate C++ Game Programming Tutorial 18"
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** Chili argues why this situation best lends itself to a composition relationship: the abstract fighter class can have a pointer to an abstract weapon class (which has derived classes for various types of weapons) | ** Chili argues why this situation best lends itself to a composition relationship: the abstract fighter class can have a pointer to an abstract weapon class (which has derived classes for various types of weapons) | ||
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| − | * Adjusting the MemeFighter code to include the Weapon class [https://youtu.be/cdOB_gKnJOM?t=4m20s 4:20] | + | * Adjusting the MemeFighter code to include the <code>Weapon</code> class [https://youtu.be/cdOB_gKnJOM?t=4m20s 4:20] |
<div class="mw-collapsible-content"> | <div class="mw-collapsible-content"> | ||
** Adding MemeFighter member functions GiveWeapon(), PilferWeapon() [https://youtu.be/cdOB_gKnJOM?t=8m03s 8:03] | ** Adding MemeFighter member functions GiveWeapon(), PilferWeapon() [https://youtu.be/cdOB_gKnJOM?t=8m03s 8:03] | ||
Revision as of 21:56, 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.
Contents
[hide]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
[Expand]
- Creating a "Virtual Function" in the
MemeFighterclass 0:23
- Enabling "Dynamic Dispatch" by using
virtualon the member function in the base class 3:17
- Applying the
overridekeyword 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
[Expand]
- Design choices in class hierarchy: inheritance vs. composition 0:43
- Adjusting the MemeFighter code to include the
Weaponclass 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
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()andWeapon::GetRank()(pure) virtual functions (this would reduce the amount of per-instance data to just the vtable ptr)
