Using C signal handler in my class - c++

Ben wrote:
> The signal() is the one in signal.h (csignal), in my class I defined a
> SIGALRM handler and then in my constructor I wrote signal(SIGALRM,
> myHandler), but the compiler gave me the error:
> error: argument of type 'void (myClass:(int)' does not match 'void
> (*)(int)'
> Where have I done wrong?

You've not read the FAQ before posting. Search for "callback" in
the FAQ, it should hopefully clear some stuff up.

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

On Oct 20, 7:53 am, "Victor Bazarov" <v.Abaza...@comAcast.net> wrote:
> Ben wrote:
> > The signal() is the one in signal.h (csignal), in my class I defined a
> > SIGALRM handler and then in my constructor I wrote signal(SIGALRM,
> > myHandler), but the compiler gave me the error:
> > error: argument of type 'void (myClass:(int)' does not match 'void
> > (*)(int)'
> > Where have I done wrong?
>
> You've not read the FAQ before posting. Search for "callback" in
> the FAQ, it should hopefully clear some stuff up.
>
> V
Thanks, V. Just wondering is there a direct link to the FAQ? I found
it using search.

On 2007-10-19 23:07, Ben wrote:
> The signal() is the one in signal.h (csignal), in my class I defined a
> SIGALRM handler and then in my constructor I wrote signal(SIGALRM,
> myHandler), but the compiler gave me the error:
> error: argument of type 'void (myClass:(int)' does not match 'void
> (*)(int)'
> Where have I done wrong?

signal() expects a function pointer and not a member function pointer.
You can not have a member function as a callback for C functions, only
plain functions will work.

--
Erik Wikström

Erik Wikström wrote:
> On 2007-10-19 23:07, Ben wrote:
>> The signal() is the one in signal.h (csignal), in my class I defined a
>> SIGALRM handler and then in my constructor I wrote signal(SIGALRM,
>> myHandler), but the compiler gave me the error:
>> error: argument of type 'void (myClass:(int)' does not match 'void
>> (*)(int)'
>> Where have I done wrong?
>
> signal() expects a function pointer and not a member function pointer.
> You can not have a member function as a callback for C functions, only
> plain functions will work.
>
Plain functions with extern "C" linkage.

--
Ian Collins.

On Oct 20, 8:48 am, Ian Collins <ian-n...@hotmail.com> wrote:
> Erik Wikström wrote:
> > On 2007-10-19 23:07, Ben wrote:
> >> The signal() is the one in signal.h (csignal), in my class I defined a
> >> SIGALRM handler and then in my constructor I wrote signal(SIGALRM,
> >> myHandler), but the compiler gave me the error:
> >> error: argument of type 'void (myClass:(int)' does not match 'void
> >> (*)(int)'
> >> Where have I done wrong?
>
> > signal() expects a function pointer and not a member function pointer.
> > You can not have a member function as a callback for C functions, only
> > plain functions will work.
>
> Plain functions with extern "C" linkage.
>
> --
> Ian Collins.

Speaking of extern linkage, do I need to apply this to those c headers
like "unistd.h", "fcntl.h"?

On 2007-10-20 00:32, Ben wrote:
> On Oct 20, 7:53 am, "Victor Bazarov" <v.Abaza...@comAcast.net> wrote:
>> Ben wrote:
>> > The signal() is the one in signal.h (csignal), in my class I defined a
>> > SIGALRM handler and then in my constructor I wrote signal(SIGALRM,
>> > myHandler), but the compiler gave me the error:
>> > error: argument of type 'void (myClass:(int)' does not match 'void
>> > (*)(int)'
>> > Where have I done wrong?
>>
>> You've not read the FAQ before posting. Search for "callback" in
>> the FAQ, it should hopefully clear some stuff up.
>>
>> V
> Thanks, V. Just wondering is there a direct link to the FAQ? I found
> it using search.

Normally the FAQ can be found at www.parashift.com but it seems to be
down at the moment, till it comes up again use the copy at
http://www.coders2020.com/cplusplus-...ned/index.html

--
Erik Wikström

Ben wrote:
> On Oct 20, 8:48 am, Ian Collins <ian-n...@hotmail.com> wrote:
>> Erik Wikström wrote:
>>> On 2007-10-19 23:07, Ben wrote:
>>>> The signal() is the one in signal.h (csignal), in my class I defined a
>>>> SIGALRM handler and then in my constructor I wrote signal(SIGALRM,
>>>> myHandler), but the compiler gave me the error:
>>>> error: argument of type 'void (myClass:(int)' does not match 'void
>>>> (*)(int)'
>>>> Where have I done wrong?
>>> signal() expects a function pointer and not a member function pointer.
>>> You can not have a member function as a callback for C functions, only
>>> plain functions will work.
>> Plain functions with extern "C" linkage.
>>
*Please* don't quote signatures.
>
> Speaking of extern linkage, do I need to apply this to those c headers
> like "unistd.h", "fcntl.h"?
>
No, they will have their own C++ wrappers.

--
Ian Collins.

Hi people! I have the same problem, but I haven't solved it. First of all, I want to say that before writing here I was searching for the solutions, I have read the C++ FAQ and so on, but I still haven't solved it.

I always get the fallowing failure:

error: argument of type ‘void (WATCHDOG:()’ does not match ‘void (*)(int)’

Here is the text of the program (before trying to edit it so as it can work)


void
WATCHDOG::cleanup() {
/* Show obtained data */
if (debug > 0) {
nei->ShowAllNeighbours(&neigs);
}
printf("\n\tFinishing watchdog...\t\tok!\n\n");
ShowStatistics();
close(sock);
nei->DeleteAllNeighbours(&neigs);
if (printPercentage) {
fclose(statistics);
}
exit(0);

}

void
WATCHDOG::setSignals() {
signal(SIGHUP, SIG_IGN);
signal(SIGINT, Cleanup);
signal(SIGTERM, Cleanup);
signal(SIGKILL, Cleanup);
signal(SIGQUIT, Cleanup);
}


This was the first variant of the code. After I got 4 errors in the last 4 lines I was trying to look for the solution. And accoeding to this: http://www.parashift.com/c++-faq-lit...o-members.html I thought I found it. Here is the modification:


void
WATCHDOG::cleanup() {
/* Show obtained data */
if (debug > 0) {
nei->ShowAllNeighbours(&neigs);
}
printf("\n\tFinishing watchdog...\t\tok!\n\n");
ShowStatistics();
close(sock);
nei->DeleteAllNeighbours(&neigs);
if (printPercentage) {
fclose(statistics);
}
exit(0);

}

void
WATCHDOG::Watchdog_memberFn_wrapper() {
object_which_will_handle_the_signal->cleanup();
}


void
WATCHDOG::setSignals() {
signal(SIGHUP, SIG_IGN);
signal(SIGINT, Watchdog_memberFn_wrapper);
signal(SIGTERM, Watchdog_memberFn_wrapper);
signal(SIGKILL, Watchdog_memberFn_wrapper);
signal(SIGQUIT, Watchdog_memberFn_wrapper);
}


But it still doesn't work. Please if there is anyone that can help me, help, cause I really don't know what to do.
What's more, I have this program written on C, and it works, but I know that signal.h works a little bit different in C++.

Thank you.