Tuples, Collectors and Agents for Java

• type-safe replacement for
• reflective invocation of methods/constructors
• callback closure objects
  
• grouping objects
• parameters
• returned values
• based on Eiffel
• Eiffel has language support for Tuples (see bottom of Other Mechanisms) and Agents
• beyond Eiffel
• Collectors are reusable abstraction of Agents
• benefiting from Java 5 generics
• immutable objects
• shared across Threads
• used many times
  

Tuple

• ordered list
• heterogenous - entries of various types
• type-safe access to each entry
• fixed size

Collector

• expects and collects entries
  
• fixed number
• ordered
  
• various types
• binds 'extra' entries
• various number
• ordered
• flexible type-safe
• operations
  
• some entries may be skipped
• return a Collector for the unfilled rest of the entries
• once all is collected
• it 'settles'
• processes the entries
• returns a result of 'settling'
• after 'settling', a customized handler can be invoked
• the entries are available to the handler
  

Agent

• special case of Collector
• binds to a method/constructor
• validates parameter and return types, and optional instance type
• binds to an instance - for non-static methods
• 'settling' returns an AgentMethod object
• use AgentMethod to invoke the method/constructor

Copyright (c) 2005, 2006, 2007 Peter Kehl