QtWebSockets and custom Signals

[Kris Revi]

Anyone know?

[SGaist]

Please show some patience. Allow 24 hours to pass before bumping your own thread. This is a voluntary driven forum and people might not live in the same time zone as you.

As for your issue, connect is a QObject static method, it follows the same rule as any other C++ static method.

Your connect statement is wrong, you have a custom class with a custom signal that does not belong to QWebSocket so your connect call will not compile.

[Kris Revi]

@SGaist said in QtWebSockets and custom Signals:

Your connect statement is wrong, you have a custom class with a custom signal that does not belong to QWebSocket so your connect call will not compile.

Im so confused!
when i try connect(Socket, MySocket::connected, this, MySocket::whenConnected)

i get 2 errors

1.no member named 'connected' in 'MySocket
2. call to non-static member function without an object argument

[Kris Revi]

Bump

Anyone?

[SGaist]

As already said:

@SGaist said in QtWebSockets and custom Signals:

Please show some patience. Allow 24 hours to pass before bumping your own thread. This is a voluntary driven forum and people might not live in the same time zone as you.
As for your issue, connect is a QObject static method, it follows the same rule as any other C++ static method.
Your connect statement is wrong, you have a custom class with a custom signal that does not belong to QWebSocket so your connect call will not compile.

Please check the Signals And Slots chapter of Qt's documentation, it shows how to use the new syntax.

Your MySocket class contains a QWebSocket but is not one and does not provide a signal by named connected. Also you are missing the & for your signal and slot arguments.

[Kris Revi]

@SGaist

i've put Socket(this) under the init of MainWindow

void MainWindow::connectTo(QString selected_board)
{
    connect(Socket, &QWebSocket::connected, this, MainWindow::whenConnected);
    Socket.doConnect(QStringLiteral("ws://%1:80").arg(selected_board));
}

Now if i try to write

connect(Socket, &QWebSocket::connected, this, MainWindow::whenConnected);

i get reference to non-static member function must called; dud you mean to call it with no arguments?

if i write

connect(Socket, &QWebSocket::connected, this, &MainWindow::whenConnected);

i get no matching member function for call to 'connect'

if i write

connect(Socket, &QWebSocket::connected, this, &MainWindow::whenConnected());

i get cannot take the address of an rvalue of type 'void'

[SGaist]

@Kris-Revi said in QtWebSockets and custom Signals:

connect(Socket, &QWebSocket::connected, this, &MainWindow::whenConnected);

What exactly is Socket ? An variable ? A class ?

If a variable, then it's the only one that has the correct syntax. However, if Socket is an instance of your MySocket class: you cannot connect a signal that is from a different class.

In C++, name starting with an uppercase letter usually signals a class. Variable names usually starts with a lowercase letter, or an underscore or some other "prefix" but not uppercased letters. Even if just a convention it's one that is used almost everywhere so it would be good to follow it as well to make your code easier to work with.

[JonB]

@Kris-Revi
Further to @SGaist. I've been reading through your code/changes and I too am confused!

First show exactly what your Socket is, as he asks. However, additionally I have not seen you define a MainWindow::whenConnected() method, does that exist as a slot in MainWindow?

[Kris Revi]

@SGaist said in QtWebSockets and custom Signals:

@Kris-Revi said in QtWebSockets and custom Signals:

connect(Socket, &QWebSocket::connected, this, &MainWindow::whenConnected);

What exactly is Socket ? An variable ? A class ?

If a variable, then it's the only one that has the correct syntax. However, if Socket is an instance of your MySocket class: you cannot connect a signal that is from a different class.

In C++, name starting with an uppercase letter usually signals a class. Variable names usually starts with a lowercase letter, or an underscore or some other "prefix" but not uppercased letters. Even if just a convention it's one that is used almost everywhere so it would be good to follow it as well to make your code easier to work with.

Socket is MySocket constructor (MySocket is a class)

[JonB]

@Kris-Revi said in QtWebSockets and custom Signals:

Socket is MySocket constructor (MySocket is a class)

Sorry, but "Socket is MySocket constructor" just does not mean anything. Nor do I know what your earlier "i've put Socket(this) under the init of MainWindow" means.

If Socket is indeed a class, then you cannot write connect(Socket, ...) in any situation. connect() connects the signal of one object/instance to a slot of another object/instance. Not classes.

I think you are wanting to achieve the following:

1. You have a class MySocket. It is a QObject, so it can use signals/slots.
2. It has a member QWebSocket m_webSocket;. So it contains/encapsulates a QWebSocket, but it is not a QWebSocket itself.
3. You define a custom signal whenConnected(), which you want emitted when the socket is connected.
4. You define a custom slot in MainWindow, to connect to that signal.

So...

• Inside MySocket you want to connect m_webSocket's connected signal to a slot, also inside MySocket, which goes emit whenConnected(), to raise/emit that signal to the outside world.
• And inside MainWindow you want to define a slot which you connect there to the MySocket::whenConnected() signal.

Is that right?