Method begin

Qt/Python/pqPythonShell.cxx:113–132

* Must be called before executing a Python snippet in the shell. * Does several things: * 1. ensures that Python interpreter is initialized. * 2. ensures that the input/output streams are captured. */

   * 2. ensures that the input/output streams are captured.
   */
  void begin()
  {
    assert(this->ExecutionCounter >= 0);
    if (this->ExecutionCounter == 0)
    {
      assert(this->OldInstance == nullptr);
      Q_EMIT this->Parent->executing(true);

      if (this->isInterpreterInitialized() == false)
      {
        this->initializeInterpreter();
      }

      this->OldInstance = vtkOutputWindow::GetInstance();
      vtkOutputWindow::SetInstance(this->MessageCapture);
      this->OldCapture = vtkPythonInterpreter::GetCaptureStdin();
      vtkPythonInterpreter::SetCaptureStdin(true);
    }
    this->ExecutionCounter++;
  }

  /**
   * Must match a `begin` and should be called when done with Python snippet