1 / 10

Programming with State Machines

Programming with State Machines. Team 1279 ColdFusion November 6, 2010. What are State Machines?. Logical Model of a System Collection of Related Settings: States Connected by Triggering Events: Transitions Simple, Consistent Framework: the Machine. Initializing. Ready.

cato
Download Presentation

Programming with State Machines

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Programming withState Machines Team 1279 ColdFusion November 6, 2010

  2. What are State Machines? • Logical Model of a System • Collection of Related Settings: States • Connected by Triggering Events: Transitions • Simple, Consistent Framework: the Machine Initializing Ready

  3. Why Use State Machines? • Abstract Complex Systems • Control System State Changes • Great Match to OO Programming Arm Retracted Arm Extended

  4. The States • States for Each Class to Control • e.g. Kicker, Arm • Easy, Abstract Names • ReadyToKick not Limit1OnandTimerExpired • Everyone needs Init • Constructor/Init should use common method • Easy error recovery • May need transitional States • ArmExtending • Not just ArmRetracted, ArmExtended • Fully Encapsulate! • Easy to add or remove states later

  5. State Contents • Entry Code • Things done once on entry (optional) • Processing Code • Things done while in the State • Exit Code • Clean Up (optional) • Transition Table • Matter of taste

  6. The Transitions • Every State Needs at Least One • Never Two Between the Same States • Usually means a design problem • Probably missing a state • Detection not an Action • Actions kept in the states • Probably missing a state • Light and Clean • Watch for Overlapping Conditions! • Order of conditions important? • Order of transitions important?

  7. Transition Contents • Sensor References • Joystick or Control Panel References • Pass references in constructor • Code to Check Events • Boolean return value

  8. The Machine • Check Current State • Transition Conditions Met? • Clean up old state • Update current state • Initial entry to new state • Process Current State • Call object machines from main loop

  9. Diagrams Proc1 Proc2 Init Ready Proc3 Any State Visio is a great tool for this, but many free apps are also available, this is done in Open Office Impress

  10. Sample Code • Java, easily ported to C++ • Abstract classes & methods • Extend • Use for ideas • On NJ FIRST site • On coldfusion1279.com

More Related