In the second part of the book we move outside the space of the individual pattern to explore the relationships between patterns. Patterns are fond of company: sometimes with one pattern as an alternative to another, sometimes with one pattern as an adjunct to another, sometimes with a number of patterns bound together as a tightly-knit group. Patterns organized as a sequence, applied one after another in a narrative flow, can add an active voice to the use of patterns in design. Last but not least, there is the general issue of organizing many patterns together as pattern collections.
No pattern is an island—they are fond of company and the space between them is full of ‘life.’ The manifold relationships that can exist between patterns help to realize, reinforce, strengthen, and extend the power of an individual pattern beyond its specific focus or location in a concrete pattern arrangement or software design. In this part of the book we therefore investigate the various types of relationships between patterns, and discuss how these relationships support the effective and productive use of patterns in concrete software projects.