PHP specification pattern that allows transformation to sql

Question

I'm trying to find out what the best way would be to have a specification pattern in PHP where the specifications could (optionally) by transformed to PHP.

I am exploring some new directions and am testing how well they would work. Code and ideas are still very unclear in my mind.

Minimal interfaces would be like these:

interface IRepository {
    public function get(ISpecification $specification);
}

interface ISpecification {
    public function isSatisfiedBy($candidate);
}

If the repository hides a sql database the specification would need to transform to sql. Adding a ->toSQL() method seems ad hoc. A class that translates the specifications is also an option but it seems like a lot of overhead to finally generate the sql.

Ideas appreciated.

Answer 1

Have you looked at CodeIgniter's Active Record syntax? It looks very similar to what you want to do.