Any GUI related operations can only be done in the GUI thread (with some minor exceptions).

The easiest solution might be migrating your pthreads code to QThreads, in which case you can use ordinary signals and slots to communicate among threads.

Hi

I have made the code changes it looks like this :

In the constructor of the mainwindow,

in the class of mainwindow

In the mainwindow.cpp file

In one of the functions of the mainwindow

Constructor of iSANserver

However Im getting the following errors :

1)

2)

Thanks

Re-run qmake, this will usually solve your problem (and most of the v-table like errors you may encounter).

However, the NotifyServerConnected signal slot should be public, not private.

Lukas Geyer wrote:

However, the NotifyServerConnected signal should be public, not private.

To emit signals, place

Incidentally, I think EmitServerConnected() and NotifyServerConnected() are poorly chosen names. EmitServerConnected() should probably be called serverConnected() or connected(). NotifyServerConnected() should be named after what it does, not what you make it react to. It is in essence a normal function, so it is best to choose a name that fits with its behavior.

Franzk wrote:

It is irrelevant whether the access is private, protected or public, because the meta object can always invoke it. The signal cannot have access specifiers (it is always protected).

That’s true. But this is a question of interface design. Public slots can and should be invoked from other classes, whereas private slots should not – even if the system supports it lacks support for encapsulation.

Franzk wrote:

NotifyServerConnected is a slot.

Hello All

Thanks for your help. The code has started working :)

Changes made

1)

2)
Slots are made public

3) Most importantly, deleted all object files, did a clean, restarted QTcreator and it compiled.
Maybe a combination of all these helped it to work :)

yannifan wrote:

1)

1. /home/sudhix/QtProjects/SANServer-build-desktop/../SANServer/SANServer.cpp:3: error: undefined reference to `vtable for SANServer'

Im not sure why the vtable error is comming for the SANServer.

Running qmake would solve this, it usually occurs because of moc skipping the class.

Lukas Geyer wrote:

However, the NotifyServerConnected signal slot should be public, not private.

You can connect signals to private slots.

kkrzewniak wrote:

You can connect signals to private slots.

Lukas Geyer wrote:

That’s true. But this is a question of interface design. Public slots can and should be invoked from other classes, whereas private slots should not – even if the system supports it lacks support for encapsulation.

Yes I’m aware of your view that one should not connect foreign signals to private slots, but you have not mentioned it in your original post concerning making the slot public. This may lead to a false assumptions that such connections are impossible.