Re: equivalent of "this" in goops?

[Neil Jerram]

Andreas Rottmann wrote:
> Greg Troxel <address@hidden> writes:
>
> > In a class representing a node, I want to have a slot with an
> > init-thunk, [...] So, I'd like to pass 'this' in c++ terms, and I don't see how 
> > to do
> > that from reading goops.info.
>
> FWICT (not being a GOOPS expert), this is not possible without
> extending GOOPS: the init-thunk of a slot is specified at class
> creation time, and the earliest time "this" is avaiable is in the
> "initialize" generic. However, since the init-thunk is called at
> initialization time, "this" would be available at the time it is run,
> but there is no way to pass it, since the init-thunk, is, well, a
> thunk ;). I could imagine a init-function (name to be argued), which
> gets passed all arguments from "initialize" could be a useful
> extension.

Absolutely right.  Your best bet at this point is to customize the 
initialize method for the class:

(define-method (initialize (this <node>) initargs)
  (next-method)
  (slot-set this 'name-of-slot-with-init-thunk
            (init-function this)))

(It's probably also possible to use the MOP to support #:init-proc as a 
new slot option, but that would require more thought.)

Regards,
        Neil