1 Fall 2009ACS-1805 Techniques for designing code Storyboards Text (aka pseudocode) Diagrams Flowcharts (a procedural technique shown in text) Directed lines indicate flow of execution UML activity diagrams (an OO technique) UML is an OO standard for diagramming for OO systems Directed lines indicate flow of execution

2 Fall 2009ACS-1805 Techniques for designing code Do the following steps in order alien moves up alien says "Slithy toves?" robot's head turns around robot turns to look at alien Do together robot moves toward the alien robot legs walk alien moves down If robot is shorter than rock robot’s neck moves up robot’s neck moves down robot turns to face the camera robot blushes robot says “Houston, we have a problem!” A storyboard in text form:

3 Fall 2009ACS-1805 Flowchart for Action Sequence Action 2 Action 1 A simple sequence of actions. Looks the same in UML. …

4 Fall 2009ACS-1805 Action Sequence A simple sequence of actions is a Do in order structure in Alice

5 Fall 2009ACS-1805 UML for Parallelism Action nAction 1 If a set of actions are to be done at the same time they can be represented in a UML activity diagram as …

6 Fall 2009ACS-1805 Text Flowchart Action nAction 1 If a set of actions are to be done at the same time they can be represented in a flowchart as …

7 Fall 2009ACS-1805 Parallel Set of Actions A Do together structure in Alice specifies that certain actions are to be done at the same time… i.e. in parallel

8 Fall 2009ACS-1805 Flowchart for If/Else expression action(s) when falseaction(s) when true false true An if/else results in one of two actions being executed depending on the truth or falsity of some expression

9 Fall 2009ACS-1805 UML for If As a UML activity diagram [false expression] [true expression] Actions for false expressionActions for true expression

10 Fall 2009ACS-1805 If/Else expression

11 Fall 2009ACS-1805 Flowchart for Loop index < limit? Loop action(s) false true Loop action(s) executed while an index goes from 0 up to a limit Set index to 0 Increment index

12 Fall 2009ACS-1805 UML for Loop Loop action(s) [index >= limit] [index < limit] Loop action(s) executed while an index goes from 0 up to a limit Set index to 0 Increment index

13 Fall 2009ACS-1805 Loop Loop action(s) executed while an index goes from 0 up to but not including a limit *Also: see the more complicated version of loop Need to build this expression

14 Fall 2009ACS-1805 A UML diagram for Robot Discovering Alien Alien moves up Alien says “Slithy toves?” Robot turns head around Robot faces alien Alien moves down Robot faces camera Robot blushes Robot says “Houston, we have a problem!” Robot moves 1m towards alienRobot leg movesRobot other leg moves Index  1 Limit  distance between alien and robot Increment index [Index < limit] [Index >= limit] Need to modify this to accommodate the spider robot moving its head up/down as done on pages 69-71