» CS 330 Lecture 21 – Object-oriented Programming

CS 330 Lecture 21 – Object-oriented Programming

March 24, 2014 by Chris Johnson. Filed under cs330, lectures, spring 2014.

Agenda

what ?s
homework 3 – due before April 4
textbook definition of OOP
theorize this
what does this do?
Game of Life with Conditionals

TODO

Read http://www.insomniacgames.com/tech/articles/0308/three_big_lies.php. (This page rendered improperly for me; I had to highlight the text to read it.)
Read http://hacksoflife.blogspot.com/2008/04/what-is-oop-good-for.html.
What do you think? 1/4 sheet.

Theorize This

On your own: How might polymorphism work?

With a neighbor: convince your neighbor that your theory is right.

What Does This Do?

class IntAndDouble {
  public:
    IntAndDouble() {}
  private:
    double d;
    int i;
};

int main(int argc, char **argv) {
  std::cout << sizeof(IntAndDouble) << std::endl;
  return 0;
}

class TwoIntsAndDouble : public IntAndDouble {
  public:
    TwoIntsAndDouble() {}
  private:
    int j;
};

int main(int argc, char **argv) {
  std::cout << sizeof(TwoIntsAndDouble) << std::endl;                                                                                             
  return 0;
}

class IntAndDouble {
  public:
    IntAndDouble() {}
    virtual int Get() const {
      return i;
    }   
  private:
    double d;
    int i;
};

class TwoIntsAndDouble : public IntAndDouble {
  public:
    TwoIntsAndDouble() {}
    virtual int Get() const {
      return j;
    }   
  private:
    int j;
};

int main(int argc, char **argv) {
  std::cout << sizeof(IntAndDouble) << std::endl;
  std::cout << sizeof(TwoIntsAndDouble) << std::endl;                                                                                                                             
  return 0;
}

Polymorphism without Conditions

Code

Sizeof.cpp

#include <iostream>

class IntAndDouble {
  public:
    /* IntAndDouble() {} */
    /* int Get() { return i; } */
  private:
    /* double d; */
    int i;
    int j;
};

int main(int argc, char **argv) {
  std::cout << sizeof(IntAndDouble) << std::endl;
  return 0;
}

Haiku

Dad said, “You can’t go”
I went and dug up his dad
“Gramps, make him say yes”