Composing Game Themes


The overview we've just been through gives a high-level view of how you compose themes. We now go through each step again with our Crystal Game example, reiterating some rules and pointing out some more detailed features that we didn't mention in the overview.

The first thing you have to do is pick the themes to be composed. This gives a context for the composition as a whole. You will be able to specify more composition relationships between elements within the context of the selected themes, which will be about matching particular design elements for a more fine-grained composition.

Figure 6-13 illustrates a composition relationship between some of our game concept-sharing (or base) themes: start, distribute-crystals, and enter-location.

Figure 6-13. Composing themes.


There are a few things to note here.

First, while this particular composition is between three themes, there is no upper limit to the number of themes that can be composed with a single composition relationship.[2] There is, of course, a lower limit of two.

[2] When we talk about overriding themes and about composing crosscutting themes later, we see refinements to this level of flexibility.

Second, notice the ThemeName["game"] text tag on the relationship. The result of every composition is contained in a new theme, which you can name here. In this example, the name of the composed theme is game. If you do not specify a name, the name of the composed theme defaults to a concatenation of the names of the themes that were composed.

Finally, notice that there is an arrowhead at each end of the relationship. This means the kind of integration required is a merge of the elements. In this case, all themes have designs relevant to the application, so all their design elements must be included. Another integration possibility is override, where matching elements in one theme are essentially replaced by the overriding theme. We'll be using both merge and override integration for the game later.



Aspect-Oriented Analysis and Design(c) The Theme Approach
Aspect-Oriented Analysis and Design: The Theme Approach
ISBN: 0321246748
EAN: 2147483647
Year: 2006
Pages: 109

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