Design Pattern
Command
user interface toolkits
support undo operations
parameterize requests
Composite
Chain of responsibility
used in our project
implementation
representing requests
request objects
qt's event system
a single handler function
hard-coded operation invocation
connecting successors
implementing the successor chain
define new links
use existing links
consequences
liabilities
unhandled maybe
benefits
flexibility in assigning responsibilities
Reduce coupling
collaborations
participants
Client
ConcreteHandler
Handler
structure
applicability
request automatical ascertain
handler specified dymatically
request to one
multi handlers
motivation
help facility
Intent
decouple requests
receiver
sender