On Design Patterns

Weekly Dev Tips

On Design Patterns

Design Patterns offer well-known, proven approaches to common problems or situations in software application development. Having a broad knowledge of the existence of patterns, and at least a few you're proficient in, can dramatically improve your productivity.

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Show Notes / Transcript

I'll admit I've been a fan of design patterns for a long time. The idea of design patterns transcends software development, and in fact the so-called Gang of Four book, Design Patterns, takes its organization and inspiration from the 1977 book, A Pattern Language. That book, by Christpher Alexander, describes common patterns in towns, buildings, and construction methods, but the idea that there are common patterns to solving similar problems applies equally to software as well as traditional building construction and architecture.

One thing that really appeals to me about design patterns is their ability to reduce waste. As software developers, we tend to want to increase efficiency and productivity, and one of the most frustrating parts of writing software (for me, at least) is when I'm stuck on a problem. This frustration is even greater when it's a problem I feel like I should know the answer to, or that I know is relatively common, so someone has solved it before. Design patterns are a great way to help you avoid reinventing the wheel (or, in many cases, a giant square that you're hoping will work as a wheel).

Unfortunately, you can't always use your usual search engine skills to come up with a design pattern. You usually have to at least be aware that it exists so that you can start to recognize scenarios where it might apply. Once you know that a pattern exists, and have at least a vague sense of when it's used, then you can easily search for more information on how to apply the pattern when you think you might have a situation that warrants it. Thus, the first step in your path to pattern mastery is exposure. You need to spend at least a little bit of time learning the names of the patterns that exist, and where they're used.

If you haven't already, you'll probably find a few design patterns that you use all the time. You can go deep in your knowledge of how and when to use these patterns. Last week, I talked about becoming a T-shaped developer as a means of differentiating yourself among competitors. Your knowledge of design patterns should have a similar T-shape, but for different reasons. You want the wide breadth of knowledge so you can speak intelligently about patterns and know what terms to search for when you want to go deep. But many patterns have fairly specific uses, so there's no need for you to try and become an expert in all of them if you're not solving the kinds of problems for which some patterns are designed.

I'm sure I'll have more tips about design patterns in upcoming shows, but one last reason why you owe it to yourself to gain at least a cursory knowledge of them is their value as a higher level language tool. When you know a design pattern by name, and how and why one would use it, you can discuss possible solutions with your team in a far more efficient and clear manner. The actual implementation of many patterns can involve several different types organized in a particular fashion, usually with specific inheritance or composition relationships. How these types are used by your system is another aspect of the pattern's implementation. Without knowing the pattern and its name, communicating a proposed solution to another developer would require describe at least most of this detail. However, if both developers are familiar with the pattern in question, one can simply say to the other, "have you thought about applying the XYZ pattern here?" and convey the same intent with less chance for confusion and with fewer words.

If you want to learn more about design patterns, I recommend the Design Pattern Library on Pluralsight as a good place to start. You can also reach out to me if you think your team would benefit from a private workshop on design patterns.

Show Resources and Links

• Design Patterns by Gamma, Helm, Johnson, Vlissides (Gang of Four)
• A Pattern Language by Christopher Alexander
• Design Patterns Library (Pluralsight)