Midterm Review - Sp2001

Coding Sensor and Turtle

• Waits for the user to press down and up on the left ("red") button (Hint: Sensor redButtonPressed and whileFalse: can take an empty block, e.g., [ "nothing" ])
  
• Draws a square of 100 pixels per side at the point where the user clicks (Sensor mousePoint) using a Pen (Hints: place: sets the Pen down at a point without drawing, down puts the Pen down, go: goes forward, turn: turns to the right). The click point should be the lower right corner of the square.
  

Dealing with the European Vacation

Design the ability to Phone Home

• The Television knows its channel and its volume setting. It knows how to turn on and off, and how to set the current channel and volume, and return it.
• The SettopBox knows its Television and its ID on the CableNetwork. It can tell the TV to turn on/off, to turn the channel on the TV, and to report its ID when requested.
• The VCR knows its channel, its start record time, and its stop record time. It knows how to play, record, fast forward, rewind, set start time, set stop time, and set record channel.
• The EntertainmentPhone knows the VCR. It knows how to accept a call, and how to tell the VCR to set the record start and stop times and the record channel.

Design Critique

Write Smalltalk Code

UML Class Diagramming

• A Student has a name, a student number, a major, and a transcript. A student knows how to change her major, can report her name or student number, and can provide a grade for a given course.
• A Transcript has a collection of course grades. It knows how to add a course grade, and how to look up a grade for a given course.
• A Major has a department name and a list of courses that are required. It only has accessors.
• A Course has a name, and a number of credit hours associated. It knows how to respond with its name.
• A CourseGrade has a course and a grade associated. It has accessors for each.

UI Toolkit Structure

History of Objects

O-O Systems

Hotel Doors OOA/D

• Each door lock has a connection to a central lock database
• A master key should open any door.
• A customer is given one or more keys that should open the door that she is assigned to
• If a customer loses a key, all the current keys should be made invalid, and only the new keys should be accepted.
• When a customer checks out, all the current keys should be made invalid, and only the new keys should be accepted.

A customer gets a card key, takes it to the door, puts it in the door lock which checks if it's valid, then the door opens because it is valid.

Analyze Student/Classroom Code

 | s c |
c := Classroom new name: 'CS2390'.
s := Student new name: 'Fred'; section: 'a'; number: '123456789'.
c add: s.
s := Student new name: 'Wilma'; section: 'b'; number: '3456789012'.
c add: s.
s := Student new name: 'Barney'; section: 'a'; number: '012345678'.
"...More code here..." 

History of Object Systems

• What is Sketchpad?
• What is Simula?
• What do they have to do with C++?

Short Essays

Reading Code

 | anArray aString |
anArray := #('abc' 'def' 'ghi','jkl').
aString := ''.
anArray do: [:each |
	aString := aString, each.].
Transcript show: aString.

 | i test |
i := 1.
test := (i < 10).
[test] whileTrue: [Transcript show: 'hello'.
	i := i + 1.].

Definitions

Drawing in Smalltalk

Analyze Robot Car

• Six wheels A-F (three per side) which can go forward or backward independently. There is a Controller that can also activate all wheels at once.
  
• Two sets of sensors. Sensors can be on or off.
  
• An array of twelve distance sensors 1-12 around the perimeter. Distance sensors report distance to nearest obstacle in direction of sensor.
  
• An array of four light sensors pointed upward and outward: L3, L6, L9, and L12. Light sensors report brightness.
  
• A solar panel on an axis and motor capable of turning 360 degrees.
  

Create a class diagram for the robot.

• What classes do you need? What service do each need to provide? What attributes do each need to know?
  
• Where are there generalization-specialization relationships? Where are there part-whole relationships?
  

Code for Robot Car

 moveBackAfterBumpingFront: sensor
        sensor = 11
        ifTrue:
        [ "Assume that we1ve bumped our front left bumper"
        "Shift all wheels into reverse gear"   
        #('a' 'b' 'c' 'd' 'e' 'f') do: [:each | each shiftRear.]
        "Activate all wheels for one second."
        wheelsController activateFor: 1.
        "Shift left side wheels into forward gear."
        #('a' 'b' 'c') do: [:each | each shiftForward.].
        "Makes left wheels go forward while right wheels go reverse -- left turn."
        wheelsController activateFor: 1.
        ]. 
 

        sensor = 1 ifTrue:
        [
Your code goes here
        ]  

Links to this Page

• Reviews last edited on 24 July 2007 at 2:44 pm by balladeer.cc.gatech.edu
• Jack Gruendler last edited on 17 December 2005 at 10:33 am by adsl-065-007-134-025.sip.asm.bellsouth.net
• Fall 2005 Discussion 4 last edited on 6 December 2005 at 3:45 pm by r36h51.res.gatech.edu
• Discussion 4 - David Figlar last edited on 10 October 2005 at 6:20 am by r52h163.res.gatech.edu
• Midterm Review last edited on 7 December 2005 at 10:44 pm by frankfort-win.cc.gatech.edu