Tooled Composite Design Pattern Andy

Tooled Composite Design Pattern Andy Bulka Austhink Software [email_address]

By GOF author John Vlissides http://www.research.ibm.com/designpatterns/pubs/ph-sep99.pdf

“direct manipulation” metaphor. ,[object Object],[object Object],[object Object],[object Object]

Representing shapes COMPOSITE – design pattern

Representing “Tools” ,[object Object],[object Object],[object Object],[object Object]

Representing “Tools” STATE – design pattern

How tools and shapes interact ,[object Object],[object Object],[object Object],[object Object]

Visitor ,[object Object],[object Object]

Example Sequence ,[object Object],[object Object],[object Object],ToolHover -------------- VisitShape() cursor = HAND VisitEdge() cursor = ARROW

Example Sequence continued ,[object Object],[object Object],[object Object],[object Object]

RTTI as alternative to Visitor ,[object Object],[object Object],ToolHover -------------- Visit() if target == Shape // use of RTTI … else if target == Edge ….. ToolHover -------------- VisitShape() … VisitEdge() ...

RTTI as alternative to Visitor ,[object Object],[object Object],[object Object],[object Object]

Events ,[object Object],[object Object],Classic STATE pattern, passing through method invocations to the current state object

Event Handling ,[object Object],[object Object]

State Pattern – switching state Notice calls to “SetTool”

Prototype Pattern ,[object Object],[object Object],[object Object]

Command Pattern ,[object Object],[object Object]

Reflections ,[object Object],[object Object]

Tooled Composite Design Pattern Andy

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