Sam's answer is spot on and pretty much what I would have recommended. A
couple of things to note. Unlike Ruby and Python, method definitions don't
belong to a particular type and it's not idiomatic to make a module
(namespace) per type. Modules tend to be a bit broader and are used to
collect a bunch of related types and generic functions which can all live
at the top level in the module. This bugs some people, but I think it's
pretty easy to work with. The one bit of awkwardness here is that there is
no way (currently) to create a generic function in a particular module
without adding methods to it. Sam's solution to this is to do
something(::Person) = error("not implemented")
You can customize this to say something like "subtypes of Person must
implement something" or whatever. If you really wanted a no method error
here, you could define a method that can't possibly be invoked, such as
this one:
something(::Union()) = nothing
That's a one-argument method whose argument is an element of the union of
no types – i.e. the "bottom" or empty type. Since on values match this
signature, this method cannot be called. This is a pretty hacky way to do
this and we should probably just have an official way of creating a new
generic function with no methods.
On Fri, Dec 12, 2014 at 11:03 PM, Charles Snider <cjsn...@gmail.com> wrote:
> Very cool Sam!
>
> Julia is new to me, but I really like ruby and was trying to do things I
> would do in ruby in julia, just didn't know how.
> This sheds all new light on the language!
>
> I really appreciate you taking your time to look at this, really very
> helpful.
>
> Thank you,
>
> - Charlie
>
