Software Patterns

Name: A pattern needs a memorable and meaningful name to allow us to clearly identify and discuss the pattern and, more importantly, to use its name as part of our design language when discussing possible solutions to design problems.

Context: This sets the stage for the pattern and describes the situations in which the pattern may apply.

Problem: Each pattern is a solution to a particular problem, so part of the pattern’s definition must be a clear statement of the problem that the pattern solves and any conditions that need to be met in order for the pattern to be effectively applied. A common way to describe the problem that a pattern solves is to describe the design forces it aims to resolve, each
force being a goal, requirement, or constraint that informs or influences the solution (such as a particular sort of flexibility needed or a particular type of interelement decoupling you want to achieve).

Solution: The core of the pattern is a description of the solution to the problem that the pattern addresses. This is usually some form of design model, explaining the elements of the design and how they work together to solve the problem.

Consequences: The definition of a software pattern should include a clear statement of the results and tradeoffs that will result from its application, to allow you to decide whether it is a suitable solution to the problem. Consequences may be positive (benefits) or negative (costs).