Re: Question about &rest, &key, and &allow-other-keys

From: rif (rif_at_mit.edu)
Date: 01/19/04 

Date: 18 Jan 2004 22:47:17 -0500

OK, thanks for the info.

The reason I don't just put the default arguments into the constructor
for the call is that I need a bunch of different "sets of defaults".
The structure holds a bunch of parameters that control how a
computation goes. In a given experimental setting, there will be a
number of these parameters that take on the same defaults, and then
I'll also need to vary one or two more. So if I have scenarios A and
B and C, I need different sets of defaults for each scenarios, with
the additional ability to specify individual parameters manually. For
this reason, I don't think :CONSTRUCTOR can help me either, as I need
several different sets of defaults.

I can see three possible solutions, and I'd be interested in hearing
which other people might choose and why, or any other ideas.

1. Suck it up and write functions that contain the defaults I need
    both in the parameter list and in the apply call, which is what
    I'm already doing:

> (defun make-my-foo (&rest params &key (d 10) (g 3) &allow-other-keys)
> (apply #'make-foo :d d :g g params))

2. Write a macro to take a minimal specification of what I want and
    generate the functions.

3. Switch to CLOS, make each separate set of defaults a new class
    that inherits from the base "control object", with the same fields
    but different defaults.

Cheers,

rif

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