Wednesday, May 24, 2006

Design Patterns: Part 1

On user interface design languages...

"What do we mean by "design patterns"?

Martijn van Welie
Design patterns describe solutions. Solutions that we know can work ‘positively’ for specific problems in specific contexts. The solutions are documented as a ‘pattern’ where all aspects can be described, even implementation issues if that is helpful and relevant.

The nice thing about explicitly relating a solution to a specific problem and context is that patterns are nearly always in ‘the grey area’; they are never totally good or totally bad. When I first started writing patterns I was more thinking black-n-white about solutions and didn’t document certain solutions. Even pop-ups are good under certain circumstances. One of the most difficult things to nail down when writing patterns is finding out when the pattern actually works well. Take the pop-up example, under which conditions does it work? When you want users to be able to take a side-rout while still keeping their current task at the back? Or for provide help? Or...? Not easy to nail down well....

Besides being grey-area-stuff, patterns are (or should I say, ‘should be’) very practical. That means that the solution should be so clear to the reader that she can apply the solution without the need of further (relevant) clarification. Therefore, patterns that have solutions that feel like ‘homework’, such as “Make sure X is clear to the user”, and to which anyone who has to apply the pattern will ask ‘yeah, but how do I do that?’, are not a very good patterns. At least, that is my view.

One thing that has kept me thinking for already a while is how patterns related to guidelines or principles. Regarding guidelines it feels to me that if patterns are in the grey-area, guidelines are usually more clearly black or white. Guidelines generally do not list any context nor specific problem and seem to be a ‘general truth’. So if you’d try you could write guidelines disguised as patterns, for example “Direct Feedback”. I definately made this mistake myself. I’ll leave it to the reader to find the patterns I wrote which are not really patterns but more like guidelines....they are still online!"   continued ...   (Via LukeW)


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