Friday, February 17, 2006

DDD Specification pattern

I just read a nice blog entry from Segio Bossa giving an example of the DDD Specification pattern. I wanted to keep his article in here so I could reference it in the future.

Following the specification discussion, in his book, Eric explores the Specification pattern more in depth and analyze the possibilities of doing composite Specifications. Then I remembered something I saw a while back on the Apache Commons project. The org.apache.commons.collections package (I wonder why is it there?) has a Predicate interface that fit's nicely with these concepts. Instead of a .isSatifiedBy() method you are given a evaluate(object) method.

I haven't really explored the idea in code by you could inherit a specifications interface and use the supplied AndPredicate, NotPredicate, etc to make composite Specifications.

Excelent!

3 comments:

Sergio Bossa said...

Very good idea Roni, I've elaborated your thoughts in my blog:

http://sbtourist.blogspot.com/2006/02/implementing-specifications-with.html

Take a look if you care.

Regards!

Sergio B.

Sergio Bossa said...

This is the link ;)

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