Object oriented-programming-vs-procedural-programming

Object Oriented Programming Vs
Procedural Programming

Requirement Spec
• There will be a shape on a GUI, a square, a
circle and a triangle
• When the user clicks on the shape, the shape
will rotate clockwise 360 degrees and play a
.wav sound file specific to that shape

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3

Step 1
Procedural programming OO programming

rotate(shapeNum) Square
{
rotate()
//make the shape rotate 360 degrees Circle
{
} //code to rotate a square
rotate()
} Triangle
{
playsound(shapeNum) //code to rotate a circle
playsound() rotate()
{ {
}
{
//use shapeNum to lookup which //code to play the .wav //code to rotate a triangle
playsound()
//WAV sound file to play and play it // file for the square }
{
}
} //code to play the .wav
playsound()
// file for the circle
{
}
//code to play the .wav
// file for the triangle
}

Change in Spec
• A new shape is added – amoeba shape along
with the others
• When the user clicks on the amoeba, the
shape will rotate clockwise 360 degrees and
play a .mp3 sound file and not a .wav file

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2
3

Step 2

rotate(shapeNum) Square
{rotate(shapeNum)
{//make the shape rotate 360 degrees rotate()Circle
} //make the shape rotate 360 degrees {
//code to rotate a square
rotate() Triangle
} } {
playsound(shapeNum) //code to rotateAmoeba
rotate() a circle
{playsound(shapeNum) playsound()
} {
{ //coderotate() a triangle
to rotate
{ //if the shape is not an amoeba use //code to play the .wav {
playsound() }
//shapeNum to look lookup which
//use shapeNum to up which .wav // file {for the square //code to rotate the amoeba
// file to play it to play and play it
//WAV sound file } }
playsound()
// else
} // file for the circle
{
//play amoeba .mp3 file } //code playsound().wav
to play the
{ the triangle
// file for
} } //code to play the .mp3
// file for the amoeba
}
rotate() will still work but the playsound()
will need to be changed

Issue with Implementation
• The logic for the rotate function was
implemented as:
– Determine the rectangle that surrounds the shape
– Calculate the center of the rectangle and rotate
the shape around that point

Actual logic that client wanted
• For the amoeba shape the client wanted the
rotate to be implemented differently
• The amoeba shape was suppose to rotate
around a point at one end

implemented required

Step 3

rotate(shapeNum, xpt,ypt) Square
{
//If the shape is not amoeba rotate()Circle
//calc the center point {
//code to rotate a square
rotate() Triangle
//based on the rectangle } {
//then rotate //code to rotateAmoeba
rotate() a circle
//else playsound()
} {
{ //codeint xpt,ypt; triangle
to rotate a
//use the xpt and ypt as the //code to play the .wav rotate()
playsound() }
//rotation point offset // file {for the square {
//and then rotate } //code to play the .wav to rotate the amoeba
playsound() //code
} // file for the circle//using amoeba’s x and y
{
} //code }to play the .wav
} playsound()
{
•Lot of code affected //code to play the .mp3
•Previously tested code changed // file for the amoeba
•What if the specification changed again }

Step 4 – Common behavior
OO programming

Square Amoeba

rotate() int xpt,ypt;
{ rotate()
Circle
//code to rotate a {
square //code to rotate the
rotate()
} amoeba
{ Triangle //using amoeba’s x and y
//code to rotate a circle
playsound() }
} rotate()
{ {
//code to play the .wav playsound()
playsound() //code to rotate a triangle
// file for the square {
{ }
} //code to play the .mp3
// file for the amoeba
// file for the circle
playsound() }
} {
} What the classes have in common?

Step 5 – Base class design
OO programming

Shape

rotate()
{
//common features
}

playsound()
{
//common features
}

Design the base class

Step 6 – Relationship
OO programming

Shape

rotate()

playsound()

Amoeba Triangle Square Rectangle

Inheritance : Base and derived class relationship

Step 6 – Overriding
OO programming

Shape

rotate()

playsound()

Amoeba Triangle Square Rectangle
rotate() {
//amoeba specific
//rotate code }

playSound() { Overriding: Derived class redefines one of its inherited methods
//amoeba specific
//sound code}
When it needs to change or extend the behavior of that method

Object oriented-programming-vs-procedural-programming

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