What Concerns
January 1, 2013
What Concerns?
David Heinemeier Hansson, the well known creator of Rails, recently gave a little pep-talk for the use of ActiveSupport::Concerns, making an argument that they were sufficient to satisfy the practical needs of DCI’s theory.
What he fails to explain is what Concerns really are. Truth be told, Concerns are essentially a extension of Ruby’s Module class to more fully support multiple inheritance. Whether out of indifference, simple oversight or perhaps a bit of decorum to save Matz’s sensitivities, who has a well known distaste for multiple inheritance, DHH never mentions this simple fact. Concerns are a way for Rails developers to include Modules with the same degree of functionality as inheriting from a superclass.
To say that Concerns are like DCI Roles, is akin to saying C structs are like OOP Objects. Yea, there’s a similarity there, but it’s vastly missing the point.