On Mon, 01 Nov 2010 05:27:06 +0300, Peter Federighi <[email protected]>
wrote:
Hello. I'm new to D. It's been a long time since I've coded anything
with
classes. Please excuse my ignorance.
Here's a very simplified version of what I'm trying to do:
import std.c.linux.linux;
import std.stdio;
class FOO
{
this()
{
sa.sa_handler = &handler;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
sigaction(SIGALRM, &sa, null);
}
~this()
{
sa.sa_handler = SIG_DFL;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
sigaction(SIGALRM, &sa, null);
}
private:
sigaction_t sa;
void handler(int signal)
{
writeln("Got an alarm signal.");
}
}
Is there a way to do it without removing handler() from the class? When
I try
compiling, I get: Error: cannot implicitly convert expression
(&this.handler)
of type void delegate(int signal) to void C function(int).
Thank you,
- Peter
No, unfortunately not. A delegate is a function pointer PLUS 'this'. The C
API you are using allows providing function only, without a context. As
such, you need to store 'this' pointer somewhere else. It is usually done
by means of of a special userData variable which is additionally passed to
the callback (looks like we are out of luck this time), or storing it in a
global variable:
Foo foo;
void externalHandler(int signal)
{
assert(foo !is null);
foo.handler(signal);
}
class Foo
{
this() {
assert(foo is null);
foo = this;
sa.sa_handler = &externalHandler;
// ...
}
~this() {
assert(foo is this);
foo = null;
// ...
}
// ...
}
