Building blocks

Lately i'm thinking a lot about code reuse. Not in the traditional OOP (inheritance & composition, libraries and components) but in a much more straightforward way. I guess it's safe to say that, despite the fact that OOP boasts code reuse as a fundamental win, the reality is that very little code is reusable (and very small amounts of code are actually written in a way that encourages code reusing).

I'm thinking about reusing "building blocks". YellowFish is a good example of this : most of the business apps need to authenticate/authorize users. But how many of them "reuse" this whole functionality from one project to another (i'm sorry ASP.NET Membership users but many of us also write Windows apps and we also need easy ways to extend this) ?


From the point of view of a business application developer this is "the ultimate reuse". Ideally someone should be able to "assemble" the application by working on the logic and have this building blocks for the "non logic" related parts.