Re: Alternate syntax for field access/method calls

[Per Bothner <per at bothner dot com>]

Dominique Boucher wrote:
> Also, it was not a request for changing or adding anything to Kawa. It was
> only
> a small experiment with readtables. I know a few (proprietary) Lisp systems
> that
> use the same [ ] notation. I simply wanted to know how easy it would be in
> Kawa to 
> emulate that. And I wanted to share this experience with other
> users/developers.

Yes, that's cool.  But it is still worthwhile thinking about
whether Kawa needs a more compact standard syntax.

> And I do have another solution: a simple 'with' macro that implements the
> same
> expansion:
>   (with object (method1) (method2 a b))
> =>
>   (invoke (invoke object 'method1) 'method2 a b)

Yes.  That's similar to my solution (2), but using a regular
macro name 'with' instead of '.'.  That makes it cleaner and
simplier to implement, but it doesn't save any typing in the
single-call case compared to invoke.  It only wins in the
cascading-invocation case.

I think the *:method syntax may be worth considering.  It's
compact.  It's simple.  And it's a natural extension of
the exiting class-name:method syntax - Kawa already has too
many ways to write method invocation, so we should avoid
something too new.

Note that:
  (*:method x a b)
is more compact than:
  (with x (method a b))
and is the same length (and uses fewer token) as:
  [x (method a b)]

In the cascading case:
  (*:m2 (*:m1 x a) b)
is shorter than:
  (with x (m1 a) (m2 b))
and and a few character longer than:
  [x (m1 a) (m2 b)]

With 3 calls:
  (*:m3 (*:m2 (*:m1 x a) b) c)
  (with x (m1 a) (m2 b) (m3 c))
  [x (m1 a) (m2 b) (m3 c)]

However, the *:m syntax does have the possible disadvantage
that the method names are "inside out", which is non-ideal
if the calls are basically sequential.
But in that case, instead of defining:
  (with object (method1) (method2 a b))
as:
  (invoke (invoke object 'method1) 'method2 a b)
it might be more useful to define it as:
  (let ((x object)) (invoke x 'method1) (invoke x 'method2 a b)))
--
	--Per Bothner
per@bothner.com   http://per.bothner.com/