Not Just Application Generation

I am however a huge fan of declarative metaprogramming (where you just tell the computer what you want your application to do and let existing generalized code figure out how to make that happen).

Whether you use design patterns, configuration files, databased metadata or application generation depends on your use cases and requirements. From experience it is difficult to create a truly flexible software product line that perform well without at least some application generation to remove unnecessary variability from specific applications. After all, why use a design pattern to support a variability that only occurs between applications?! That is the perfect use case for application generation and you get better performance as well as more comprehensible and maintainable code.

I think that traditional imperative programming is necessary for edge cases, but the vast majority of programming problems have already been solved. We shouldn’t be rewriting CRUD, validation, authentication, shopping carts or discussion board functionality any more. We should just be declaratively specifying the variability we want from elegantly designed base product lines - whether through language extensions in languages like Ruby, databased metadata or the all pervasive XML file.

Declarative metaprogramming is not a simple problem and it will not be solved with a single bold stroke (language workbenches not withstanding). But just keep a count of lines of XML vs. lines of code in your last project. Do the same every six months and I think you’ll see a real trend over the next two years!