What is the differnce between Signal and slot?

[Sunmuk]

Hi all,
I have a doubt about signal and slot.Whether the signal has definition or declaration only.and what is slot?.Please suggest me soon.

Thanks

[mcosta]

@Sunmuk said:

Please suggest me soon.

I suggest to read soon this page :)

[Sunmuk]

Hi,
I referred the link mentioned previously.I am clear now with the concept like "Whether signal has implementation?".But still now confused with the signal.
code snippet is
signals:
void ItemAdded( Item item);

My question is
1.How this signal is emitted?
2.Why signal has the argument?
3.What is the relation between signal and its parameter?

[mcosta]

Hi,

1. how explained in the article, a signal is emitted using the emit keyword or the Q_EMIT macro

emit <signal_name>(<parameters_list>);

Q_EMIT <signal_name>(<parameters_list>);

2. Sometimes you need to signal what is changed and not only that something is changed

3. the signal is the notification that something happened, parameters are details about the event

[s.frings74]

Signals are declaration only. Slots provide the code that shall be executed when the signal gets emitted.

When you emit a signal, then all assigned slots are executed with the arguments of the signal.

[alex_malyu]

@s.frings74 said:

Signals are declaration only.

Even though other part of explanation is correct above is wrong.
There is no magic and signal is actually a function.
User does not provide its implementation though.
It is automatically generated during mocing.
You can check look at generated code in the generated moc_*.cpp file.

[Sunmuk]

@mcosta
Thanks.....