Implementation patterns – Behavior

By | 10 September, 2013

John Von Neumann contributed one of the primary metaphors of computing a sequence of instructions that are executed one by one. This metaphor permeates most programming languages, Java included. The topic of this chapter is how to express the behavior of a program.

The patterns are:

  • Control Flow—Express computations as a sequence of steps.
  • Main Flow—Clearly express the main flow of control.
  • Message—Express control flow by sending a message.
  • Choosing Message—Vary the implementors of a message to express choices.
  • Double Dispatch—Vary the implementors of messages along two axes to express cascading choices.
  • Decomposing Message—Break complicated calculations into cohesive chunks.
  • Reversing Message—Make control flows symmetric by sending a sequence of messages to the same receiver.
  • Inviting Message—Invite future variation by sending a message that can be implemented in different ways.
  • Explaining Message—Send a message to explain the purpose of a clump of logic.
  • Exceptional Flow—Express the unusual flows of control as clearly as possible without interfering with the expression of the main flow.
  • Guard Clause—Express local exceptional flows by an early return.
  • Exception—Express non-local exceptional flows with exceptions.
  • Checked Exception—Ensure that exceptions are caught by declaring them explicitly.
  • Exception Propagation—Propagate exceptions, transforming them as necessary so the information they contain is appropriate to the catcher.

Implementation Patterns - Behavior (schema)

Source: Implementation Patterns: Kent Beck: 9780321413093: Books

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