[haiku-development] Re: R1/a4 initial planning
- From: Pete Goodeve <pete.goodeve@xxxxxxxxxxxx>
- To: haiku-development@xxxxxxxxxxxxx
- Date: Sun, 26 Feb 2012 14:25:47 -0800
On Sun, Feb 26, 2012 at 02:37:08PM -0500, Ryan Leavengood wrote:
>
> I would like to see if it is possible to implement some of the nice
> parts of signals and slots without requiring a special pre-processor
> like moc. Maybe some aspects of C++0x could be used for this, such as
> lambdas. This could be an area where Haiku could innovate because of
> our ability or desire to not worry about backwards compatibility in
> R2.
Just fTR, while trying to learn something about Qt myself (never used it),
I came across the "sigslot library": http://sigslot.sourceforge.net/
(She calls it a 'library' but it's actually simply a header file with lotsnlotsa
templates.) It's not quite the same as the Qt concept, because there's
no inter-thread invocation of slots -- they're always executed in the
calling thread -- but it might be interesting to take a look at.
As this shows, a moc isn't necessary for the concept itself, and I can't
see any fundamental reason why behind-the-scenes queueing couldn't
be added (though it would need more than a header).
I was able to whip up a quickie test program, appended below, that
wored a treat first time [once I'd read the docs properly... (:-/)].
Cheers,
-- Pete --
-------------------------
// Test of sigslot
#include <Application.h>
#include <Window.h>
#include <Button.h>
#include <Message.h>
#include "sigslot.h"
using namespace sigslot;
class SSWindow : public BWindow {
public:
BButton *btn;
SSWindow() : BWindow(BRect(40,40, 140, 80), "Test", B_TITLED_WINDOW, 0)
{
btn = new BButton(BRect(10, 10, 60, 30), "Test", "TEST",
new BMessage('butn'));
AddChild(btn);
}
signal0<> click; // A signal with no arguments
void MessageReceived(BMessage *msg) {
switch(msg->what) {
case 'butn':
click();// emit the signal
break;
}
}
bool QuitRequested()
{
be_app->PostMessage(B_QUIT_REQUESTED);
return true;
};
};
class SSApp : public BApplication, public has_slots<> {
public:
SSWindow *w;
SSApp() : BApplication("application/x-test-sigslot") {
w = new SSWindow();
w->Show();
w->click.connect(this, &SSApp::clicked);
}
void clicked() { // The "slot" method
printf("button clicked\n");
}
};
main() {
new SSApp();
be_app->Run();
delete be_app;
}
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