In my previous post on Patterns & Practices, I discussed the fact that in order to learn P&P, you have to be willing to make mistakes. In the early stages, it is beneficial to look for opportunities to apply patterns to your development so that you can begin to see how they take shape. You may not understand their benefit in the early stages, but this is a vital step, akin to the experience of the "Karate Kid" as he was told to "wax on / wax off". He spent weeks practicing the same moves over and over again, not really understanding the purpose of such repetitive tasks. What he failed to realize was that he was developing muscle memory and creating well worn neural pathways that would prove vital in his development process. This holds true for us as software developers as well. [For this early development stage, a key resource is a book such as Head First Design Patterns].
Eventually you gain some proficiency with the repetitive tasks. You begin to realize that certain patterns work better than others in certain circumstances. You might discover that some patterns can paint you into a difficult corner (Singleton is of course the prime example, though Static Gateway has its pitfalls as well). At this stage you are beginning to deconstruct the value and utility of particular patterns for certain situations and contexts. You awaken to the realization that code can have a "smell" that communicates whether a design is fitting or not. While you cannot necessarily name the "smell" it is clearly there. [At this stage, you're ready to tackle Refactoring to Patterns].
Take time to identify patterns that fit well for addressing particular smells. Look for examples in code written by others (you are taking time to read code written by others, right?). And start looking for ways that improper use of patterns can introduce smells of their own.
In my next post in this series, I will switch gears and discuss the relationship between Patterns and Practices and why you ultimately want to emphasize the Practices over the Patterns. Stay tuned!
Tags: patterns & practices, process