Qt Passing signal from Item to a container

Question

I have a QVector of pointers to type X, whose items, i.e. X's own QProcesses. These processes can terminate at arbitrary time. Now, I have constructed signal-slot connection inside class X when a process ends. However, I want to propagate it to the handler class which has a QVector of X* as a member. What is an elegant way for doing this?

Answer 1

You can connect a signal to a signal, hiding the source signal being an implementation detail:

class MyInterface : public QObject {
  Q_OBJECT
  ...
  QProcess m_process;
public:
  Q_SIGNAL void processEnded();
  MyInterface(QObject * parent = 0) : QObject(parent) {
    connect(&QProcess, &QProcess::finished, this, &MyInterface::processEnded);
    ...
  }
};

The handler class can listen to these signals and do something with them.

class Handler : public QObject {
  Q_OBJECT
  QVector<MyInterface*> m_ifaces; // owned by QObject, not by the vector
  void addInterface(MyInterface* ifc) {
    ifc->setParent(this);
    connect(ifc, &MyInterface::processEnded, this, [this, ifc]{
      processEnded(ifc); 
    });
    m_ifaces.append(ifc);
  }
  void processEnded(MyInterface* ifc) {
    // handle the ending of a process
    ...
  }
  ...
};