View Full Version : Problem with unused parameter
devilj
4th July 2007, 02:50
I have a function:
QCheckBox *Window::createCheckBox(const QString &text, const QString &key)
{
QCheckBox *checkBox = new QCheckBox(text);
connect(checkBox, SIGNAL(stateChanged(2)), this, SLOT(addKeyword(key)));
connect(checkBox, SIGNAL(stateChanged(0)), this, SLOT(killKeyword(key)));
}
When I compile I receive:
warning: unused parameter ‘key’
Any thoughts?
Thanks
guilugi
4th July 2007, 07:16
Be careful, you're not using signals & slots in the good way !
You should check the docs to understand it better, and see some examples ;-)
You cannot connect signals with explicit parameters, you have to use QSignalMapper to achieve this.
Here, you can do something like that :
connect(checkBox, SIGNAL(stateChanged(int)), this, SLOT(addKeyword(int)));
You can only specify parameter types, not parameter values !
Guilugi.
wysota
4th July 2007, 08:37
When I compile I receive:
warning: unused parameter ‘key’
Omit the parameter name or use Q_UNUSED(key) to mark the variable as unused, preventing the warning from showing up.
And correct those signal/slot connections as advised.
devilj
4th July 2007, 10:23
Thanks for the response and your patients with a newbie....
So am I to gather that a signal doesn't neccessarily trigger a slot.
For instance just because SIGNAL(stateChanged()) emits a "2" doesn't mean my SLOT(addkeyword()) automatically triggers. In essence I need to "spy" on this signal and is this where SignalSpy and Signal Mapping come in? If so, is the result of the spying a variable that can be evaluated.
Thanks
Recommended reading: Signals and Slots (http://doc.trolltech.com/4.3/signalsandslots.html).
devilj
4th July 2007, 18:48
Ok, I see!
So really what I want to do is not rely on pre-defined slots and signals but create my own subclass wigets that will do what I want...more work, but MORE POWER!
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