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Re: IS there a usual-XXX function ?
- To: Andrew L. M. Shalit <alms>
- Subject: Re: IS there a usual-XXX function ?
- From: Gary Byers <email@example.com>
- Date: Tue, 4 Sep 1990 17:03:25 EDT
- Cc: firstname.lastname@example.org, info-macl
- In-reply-to: Your message of Tue, 4 Sep 90 12:42:18 -0400
> Date: Thu, 30 Aug 90 11:55:27 CDT
> From: Richard Lynch <email@example.com>
> I'm at a point in a complex object hierarchy where I want to know if there
> IS a real usual-cut function for any of the ancestors. Will (fhavep 'usual-cut)
> tell me anything? or do I have to go through the ancestor hierarchy manually
> to find a (fhavep 'cut) or not ?
> There is no FHAVEP (to my knowledge).
> FBOUNDP will tell you if there is an accessible binding in the current
> object, or any of it's ancestors, down to the root (global) environment.
> FOWNP will tell you if the current object has its own binding for the
> function. It doesn't search ancestors.
Neither of these things (nor any straightforward combination of them that I
can think of) will tell you what function, if any, will be invoked by a given
call to USUAL-xxx.
As far as I remember, Object Lisp's lack of anything analogous to CLOS' NEXT-
METHOD-P is intended to be a feature: a call to USUAL-xxx when "there is no
USUAL-xxx" is defined to be a no-op (as opposed to signalling a NO-NEXT-METHOD
error.) The belief was that the programmer had no other reason to be concerned
about the existence of a "USUAL" function.
You (Richard Lynch) indicated that your code was complicated, but can you
explain a little more about why your program needs to know about, e.g.,