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From: king1@husc10.harvard.edu (Gary King)
Newsgroups: comp.lang.c++
Subject: G++ question
Keywords: G++, C++
Message-ID: <1991May6.183253.880@husc3.harvard.edu>
Date: 6 May 91 22:32:52 GMT
References: <74609@brunix.UUCP>
Sender: king1@husc7.harvard.edu (gary king)
Followup-To: king1@husc7.harvard.edu
Organization: Harvard University Science Center
Lines: 67
Nntp-Posting-Host: husc10.harvard.edu

HI,

I'm using the following C++ class to interface to the interval
timer and the SIGALRM signal in UNIX.  g++ doesn't mind the header
file and it doesn't mind the constructor, but when it gets
to int ticker::sethandler( void (*f)(int) ) it complains:


	ticker.cc: 'f' undeclared, outside of functions
	ticker.cc: parse error before ')'


Can anyone explain this and what to do to make it work.


Thanks in advance.... (truncated code appears below):


/*
**	ticker class
**			This class is an interface to the UNIX
**			alarm system call.  Only one is allowed at a
**			time so we make everything in it static.
*/

#include	<signal.h>

class ticker {
public:
	ticker( int, void (*f) (int) );
	~ticker();

	// user interface
	...
	static int	sethandler( void (*) (int) );

private:
	static void	set_ticker( int = 0 );
	static	int	ticks;			// how often to go off
	static  void	(*handler)(int);	// what to do when we ring
};

::::::::::::::::::
ticker.cc
::::::::::::::::::

#include	<sys/time.h>
#include	<stdlib.h>
#include	"ticker.h"

void syserr( char * );

ticker :: ticker( int ticktock, void (*func) (int) ) {
	ticker :: ticks = ticktock;
	ticker :: handler = func;
	signal( SIGALRM, ticker :: handler );
}

...
...
...

static int	
ticker :: sethandler( void (*xll)(int) ) {
	signal( SIGALRM, (ticker :: handler = func ) );
	return 0;
}