Programmer Musings

20 Years of Design Patterns

As I'm writing this in December of 2014, I've been reminded that the classic Design Patterns book came out in 1995, almost twenty years ago. I didn't see the book until a year or two later.

Reactions

I remember several reactions from the programmers I was working with at the time. Most of the programmers at my experience level and below were amazed. This was a new way of approaching the problems they were struggling with. It was a revelation.

On the other hand, one very senior developer I knew was completely unimpressed. He pointed out that these patterns were not new, and that he had used some variant of most of them for years.

The remainder couldn't quite wrap their heads around the whole thing. They couldn't tell if there was something here or if it was just another fad.

Study

We had been running an unofficial weekly get-together at lunch where we did presentations or discussions. That weekly session was taken over with a book-study session. Each week a different programmer from the group would study one of the patterns and present it to the group. We would then discuss the pattern and try to really grok them.

This had a couple of useful results. The senior guy I mentioned above eventually decided that he had changed his mind about the book. But, he said the most important thing he could see coming from the book was the shared naming. We could all talk about these ideas without explaining them each time they came up.

The pattern converts, myself included, moved to a more practical understanding of the patterns. Having a dozen or so people pick apart the patterns as a group gave us a better feel for when these tools might be useful and when they would not. As a result, no one at the company fell for the use all the patterns insanity that overtook some areas of the programming community.

Impressions

The Design Patterns book was a definite watershed event in the way programmers viewed object oriented programming. There were a few, mostly inexperienced, programmers who went overboard, adding patterns to everything they built just for the sake of adding patterns. There were also many who became better programmers by first applying the patterns and then coming to understand the reasons behind the patterns.

Although the Gang of Four book is not the only patterns book, (in fact an entire subculture of patterns research and literature has come out since 1995) it is still the best known and therefore has had the widest impact. It is simultaneously hard to believe that it has been 20 years, and hard to remember what programming was like before design patterns.