Pattern : PATTERN LANGUAGES

CONTEXT : You are trying to use the "pattern form" to describe a procedure with many steps or a complex solution to a complex problem. Some of the steps may only apply in particular circumstances. There may be alternate solutions to parts of the problem depending on the circumstances. A single pattern is insufficient to deal with the complexity at hand.

PROBLEM : How do you describe the solution such that it is easy to digest and easy to use parts of the solution in different circumstances?

FORCES :

A single large solution may be too specific to the circumstance and impossible to reuse.

A complex solution may be hard to describe in a single pattern. A "divide and conquer" approach may be necessary to make the solution tractable.

Factoring the solution into a set of reusable steps can be very difficult. Once factored, the resulting pieces may depend on one another to make any sense.

Other pattern languages may want to refer to parts of the solution; they require some sort of "handle" for each of the parts to be referenced.

SOLUTION :

Capture each problem/solution pair as a pattern within a larger pattern language.

Each pattern should solve a specific problem within the shared context of the language. Strive to ensure that each pattern could conceivably be used alone or with a limited number of patterns from the language.

EXAMPLE : This pattern language is itself an example of tackling the complex problem of writing patterns and pattern languages. It presents the solution as a number of patterns each of which describe the solution to a specific smaller problem.