NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/comp/sys/next/programm/7999

Internet Message Format | 1993-01-06 | 1.7 KB

Path: sparky!uunet!gatech!usenet.ins.cwru.edu!agate!usenet
From: [e-mail] (Izumi Ohzawa)
Newsgroups: comp.sys.next.programmer
Subject: Re: Pointers to functions in method definitions
Date: 6 Jan 1993 09:49:24 GMT
Organization: University of California, Berkeley
Lines: 32
Distribution: world
Message-ID: <[e-mail]>
References: <[e-mail]>
Reply-To: [e-mail]
NNTP-Posting-Host: moica.berkeley.edu

In article <[e-mail]> [e-mail] (Sam Streeper) writes:
>[e-mail] (A.B. McLean) writes:
>> I want to write a method that will accept a pointer to a C function.
>
>I would guess that this isn't directly possible; it looks like the Objective-C
>runtime doesn't have the ability to encode data of type function pointer.

In NextDeveloper/Examples/AppKit/Graph/Expression.h, there is an example
that uses typedefs.  It may not cover all situations, but at least
the code can remain comprehensible if you can use it.


/* function supplied by term implementor for evaluation */
typedef float EXPTermEvalFunc(int numArgs, float *args);

 .....

- addFuncTerm:(const char *)name minArgs:(int)min maxArgs:(int)max
                    evalFunc:(EXPTermEvalFunc *)func;
 /*
  * Adds a function to the set of functions this Expression can parse.
  * Functions look like "name(arg1, arg2,...)" in the text that is
  * parsed.  At evaluation time the C function func() will be called with
  * the values of the arguments. ....
  */


--
Izumi Ohzawa             [ $@Bg_78^=;(J ]
USMail: University of California, 360 Minor Hall, Berkeley, CA 94720
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