Lecture 16: Inheritance

Tuesday 04/03, 2007

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Assigned Reading:   

Slides As Shown:

• Announcements, etc: [slide view] [print view]

• Private and Multiple Inheritance: [slide view] [print view]

• Virtual Member Functions : [slide view] [print view]

Topics Covered:

• Discussed what it took to combine Project 2 with GTKmm. Here's a screenshot:
  

• Discussed private derivations and multiple derivations.

  An example of private derivation is deriving a Package class from the Box class we've been discussing:

  Package.h Package.cpp
  ptest1.cpp ptest1.txt
  ptest2.cpp ptest2.txt

  An example of multiple inheritance is having our GUI race course derive from both the GTKmm Window class and the RaceCourse class from Project~2. Then, a GUIRaceCourse object is both a Window and a RaceCourse, instead of a Window that contains a RaceCourse. It is debatable which approach makes more sense.

• Discussed compile-time versus run-time binding.

• Discussed the use of virtual member functions to achieve polymorphism in C++. We discussed in depth exactly how the virtual member function table works. Most of this was done using gdb with diagrams drawn on the white board. (So, get notes from friends.)

  Examples of the Box class using virtual identify(). The only change needed is to add the keyword "virtual" to declaration of identify() in the Box class definition: Box.h.

  Some test programs using the virtual identify() function: vtest0.cpp, vtest1.cpp, and vtest2.cpp. Note that the end of vtest2.cpp is a total hack that rewrites the virtual function table pointer of cc to make it point to the base class virtual function table. (Don't do try this at home.)