Re: Can we prefix with module names? (was Re: Shorthand for Java)

[Per Bothner <per at bothner dot com>]

Jocelyn Paine wrote:

> With these, can we now use Kawa module names as prefixes too? Selected at
> runtime? So that if modules M1 and M2 both export function f, my code can
> pass the name of one of these modules around in a variable V, and then
> call V:f?
No, at least not as currently implemented/conceptualized.

First, namespace aliases are in a different namespace:
  (define namespace foo "uri")
is equivalent to:
  (define-constant MAGIC-foo "uri")
where MAGIC is a reserved internal name.

Secondly, the alias has to be bound to a constant.
That *could* perhaps be relaxed, but I don't know how much
of the implementation would have to be changed.

A cleaner (and much more efficient) solution might be to use interfaces:
Have both modules implement an interface, and then use an alias for
that:

I.java:
public interface I {
  public Object f(Object x);
}

M1 (and M2):
(module-implements <I>)
(define (f x) ....)

(define-constant m-instance :: <I>
  (select-one-of (make <M1>) (make <M2>)))
(define namespace I "class:I")
(I:f m-instance x)

I make no guarntees whether this works.  It
probably *should* ...

--
	--Per Bothner
per@bothner.com   http://www.bothner.com/per/