Actual usage of design pattern in open source software?

Question

Does anybody know if some kind of study has been made to find out which design patterns are used in open source software? That would be interesting because it would provide a source of real-life examples of patterns implementation and it would give an idea about which patterns are the most frequently used.

Answer 1

I don't know about any study, but the most frequently used pattern seems to be Singleton and two frameworks using many patterns are Spring and Hibernate.

Java itself is full of patterns, and now opensource ;)

Answer 2

Based on Bloom's Taxonomy and Design Patterns article, the "Big Ball of Mud" could be most used pattern. IMHO it is not bad pattern. And open source projects have high chance of starting from that pattern. I would vote for "Layered Application" -- even low entry developer knows it :-)

Answer 3

I am also not aware of a study. But a very interesting project regarding design patterns is JUnit. The Unit Test framework is based on various design pattern.

See for yourself in the documentation: JUnit - A Cook's tour

Answer 4

That's not surprising as one of the key roles in the JUnit project is fulfilled by one of the GoF /gasp :)