Pattern : COMMON PROBLEMS HIGHLIGHTED

CONTEXT : You are writing a pattern language that provides several patterns that solve the same problem.

PROBLEM : How do you make readers aware that they should choose one of the alternative solutions?

FORCES :

A pattern is normally considered to be a problem-solution pair. Most pattern forms currently in use do not lend themselves to sharing a problem section amongst several competing patterns without taking some liberties with the form.

Repeating the problem in each pattern that provides a solution may confuse readers by giving them a sense of "deja vu" without explaining the cause for it. They may not realize that there are several solutions to choose from and may expend considerable energy trying to figure out how to apply all the solutions simultaneously!

Having the problem repeated in each pattern that provides a solution increase the effort required to maintain each pattern.

The problem section is not the only part of the pattern that would have to be duplicated. All patterns which solve the same problem should include the same set of forces, while the context determines their relative priority.

SOLUTION : When several patterns solve the same problem, make this obvious by pointing out to the reader that there are several solutions to this problem. You can capture the common problem and forces in one place using Separate Problem Description or Referenced Problem Description. If you choose to repeat the problem description as described in Duplicate Problem Description you should notify the reader that you have done so.

RATIONALE : It is very easy for readers to become confused if several patterns have similar or identical problem descriptions unless it is pointed out to them that these patterns provide alternative solutions.