Re: [Sbcl-devel] print-object, and builtin types

[<bdo...@la...>]

On Wed, May 24, 2006 at 04:28:01PM -0500, Matthew D Swank wrote:
> The Hyperspec says the following about print-object:
> 
> Each implementation is required to provide a method on the class 
> standard-object and on the class structure-object. In addition, each 
> implementation must provide methods on enough other classes so as to 
> ensure that there is always an applicable method.
> 
> So, should the humble extender of such methods hold any hope that they 
> will be called?

IMHO, no, because of this:

| 11.1.2.1.2 Constraints on the COMMON-LISP Package for Conforming
| Programs
| 
| Except where explicitly allowed, the consequences are undefined if any
| of the following actions are performed on an external symbol of the
| COMMON-LISP package:
| 
| ...
| 
| 19. Defining a method for a standardized generic function which is
| applicable when all of the arguments are direct instances of
| standardized classes.

Admittedly it would be nice if this weren't the case, but I think it
places a pretty large burdeon on the implementation to support this
(and still go fast).

-bcd