passing accessors to functions

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2 total messages Started by Jeffrey B Kane Wed, 28 Oct 1992 20:49

Author: Jeffrey B Kane
Date: Wed, 28 Oct 1992 20:49

13 lines
740 bytes

I have an question:

I have a common function that can act on any of a number of 
slots of a given class.  How can I define a function such that
I can pass it an accessor, the class instance, and the arguments
something like:


(defun do-proc (anAccessor aclass arg)
  (setf (anAccessor aclass) arg))

     Jeffrey

Re: passing accessors to functions

Author: Barry Margolin
Date: Thu, 29 Oct 1992 04:06

25 lines
1311 bytes

In article <Bwun61.E1q@world.std.com> jbk@world.std.com (Jeffrey B Kane) writes:
>I have a common function that can act on any of a number of 
>slots of a given class.  How can I define a function such that
>I can pass it an accessor, the class instance, and the arguments
>something like:
>(defun do-proc (anAccessor aclass arg)
>  (setf (anAccessor aclass) arg))

You can't do precisely that.  You can pass a slot name, and then use SETF
of SLOT-VALUE, e.g.

(defun do-proc (slot-name object arg)
  (setf (slot-value object slot-name) arg))

or you can pass the setf function itself:

(defun do-proc (assignment-function object arg)
  (funcall assignment-function arg object))

This would be called as (do-proc #'(setf <slot-name>) <object> <value>).
-- 
Barry Margolin
System Manager, Thinking Machines Corp.

barmar@think.com          {uunet,harvard}!think!barmar

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