Callback and Signal-Slot?

c.savur

Hello everyone,

I have question about using both callback and Signal/Slot in a Qt application.

I have a external library that calling my qt application via callback. In the Qt application as normal I am using Signal and Slot. So in order to not have any problem what is the best way to handle both callback and Signal ?

Right now, I am handling in following manner,

1 ) Registering my callback method.
2 ) when my callback method invoked by library, I generate a signal and return from my callback method.
3 ) since signal is connected to a slot, it invoke it.

So far this method is working. But I want see if you have better approach that can handle this station.
I also want to know if there is a side affect of the approach I am using right now?

Thanks.

Chris Kawa

That's pretty much the standard way to write wrappers for non-Qt mechanisms.

The only comment I have here is that the order you presented is not quite right. For single threaded programs the default connection is a direct one, meaning that the actual emit is a blocking function calling all the connected slots, so the order is actually:

Registering my callback method.
when my callback method is invoked by library, I generate a signal
since signal is connected to a slot, it invoke it.
return from my callback method.

So that's something to keep in mind, usually in a context of order of destruction of things.

c.savur

@Chris-Kawa

Hi Chris,

Actually, I am doing in the same order you wrote. :)

I will keep this topic, open so see others opinion.

Thanks