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Re: no-next-method | no-applicable-method
- To: David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>, Dick Gabriel <RPG@SAIL.Stanford.EDU>, kempf@Sun.COM, Jon L White <email@example.com>, Patrick H Dussud <DUSSUD@Jenner.csc.ti.com>
- Subject: Re: no-next-method | no-applicable-method
- From: Gregor.pa@Xerox.COM
- Date: Wed, 4 May 88 16:11 PDT
- Cc: common-lisp-object-system@SAIL.STANFORD.EDU, Danny Bobrow <Bobrow.pa@Xerox.COM>
- Fcc: BD:>Gregor>mail>outgoing-mail-2.text.newest
- In-reply-to: <19880504175137.5.MOON@EUPHRATES.SCRC.Symbolics.COM>, The message of 4 May 88 11:52 PDT from Dick Gabriel <RPG@SAIL.Stanford.EDU>, <8805041542.AA15982@suntana.sun.com>, <8805040712.AA23297@bhopal.lucid.com>, <19880503223117.3.GREGOR@PORTNOY.parc.xerox.com>, The message of 3 May 88 13:15 PDT from Dick Gabriel <RPG@SAIL.Stanford.EDU>, <19880503180516.1.GREGOR@PORTNOY.parc.xerox.com>, <8805021600.AA13865@suntana.sun.com>, <2787575636-15393416@Jenner>, <19880429213039.5.GREGOR@PORTNOY.parc.xerox.com>
- Line-fold: no
This message is an attempt to summarize the discussion on this issue. I
present what I believe we have decided so that it can be written up and
put into the specification.
As Moon says:
Date: Wed, 4 May 88 13:51 EDT
From: David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>
I think we are all agreed that CALL-NEXT-METHOD, when there is no next
method, should call a user specializable generic function, rather than
directly signalling an error as 88-002 says. The only point of contention
is what should the name of that generic function be.
As for people's opinion on the secondary question of what the name and
arguments of the user specializable generic function should be, most
people seem to have swung over now to the position that call-next-method
errors should have their own generic function with its own argument
list. In recent messages,
I have no strong opinion on this issue. My own sense of programming
style dictates that in any program I wrote, two separate generic
functions would be used.
In any event, I found the combination of Danny's and Jonl's arguments
persuasive. That is, CALL-NEXT-METHOD errors could be so obscure
that it deserves its own generic function.
So I believe we should have a generic function no-next-method. It
receives as arguments:
- the generic function belonging to the method (which is the
- the method which Moon described by saying:
I think what you mean is more precisely stated as: the method that
created the local definition of call-next-method that had no next
method. Because closures of call-next-method can be passed around
as funargs, this may not be the currently executing method at the
time NO-NEXT-METHOD is called.
- and the arguments to call-next-method. These are passed with apply.
There is a system supplied method defined as if:
(defmethod no-next-method ((gf standard-generic-function)
(error "No next method when CALL-NEXT-METHOD is called."))
Unless there are further objections to this, I believe it can go into
chapter 1 and 2.