19.6 Direct methods

The definition of the one-of constant is a method called a direct method or bare method. It is the equivalent of a function in other languages. A bare method does not create an implicit generic function, and invoking a bare method does not use method-dispatch procedure, but rather calls the method directly. We choose to use a bare method here because we are sure that one-of will never need method dispatch: it performs the same operation independent of the types of its arguments. The bare method serves to document this intent. If there were some possibility of additional methods, it would be more perspicuous to use a generic function, even if there is initially only one method. Most Dylan compilers will generate equally efficient code for a bare method and for a generic function with only one method, so the choice of which to use should be based on whether or not it would ever make sense to have additional methods that discriminate on parameter types.