How to deal with signals emitted before slots connected - c++

Question

I have a somewhat more complicated version of the following code:
void Foo::makeConnection(...) {
QTcpSocket * socket = new QTcpSocket(this);
// ...
socket->disconnect(this);
emit connectionAppeared(socket);
}
void Bar::baz() {
// ...
connect(foo, SIGNAL(connectionAppeared(QTcpSocket*)), this, SLOT(onConnectionAppeared(QTcpSocket*)));
foo->makeConnection(...);
}
void Bar::onConnectionAppeared(QTcpSocket * socket) {
if (!socket) { std::terminate(); }
socket->setParent(this);
connect(socket, SIGNAL(readyRead()), this, SLOT(readData()));
connect(socket, SIGNAL(disconnected()), this, SLOT(socketClosed()));
}
The Bar::baz asks Foo to make it a connected QTcpSocket, and after it is made, the socket's signals are connected to Bar's slots. But there is a problem with timing: the readyRead signal may very well be emitted befor it is connected to any slots, and thus is effectively lost. We "fixed" it like this:
void Bar::onConnectionAppeared(QTcpSocket * socket) {
// ... same code as before plus the following line:
emit socket->readyRead(); // Kick it to get started!
}
void Bar::readData() {
while (mSocket->bytesAvailable()) {
// ...
}
}
The problem of losing disconnected() signals is still there, but it doesn't manifests very often. Technically, I could emit disconnected() manually, and check socket->state() in the socketClosed() slot... but I just feel it's not the right way. I effectively just manually examine the current state instead of reacting to state transitions which I was the whole point of signal/slot machinery.
Are there nice ways to fix this kludge? I thought of passing signal/slot pairs to Foo::makeConnection(...) somehow, so they can be connected before socket->connectToHost() is called, but I don't know how, and I am not sure it's the good idea anyway.