qobject_cast() and typeid() problem

[wysota]

This code is invalid - as the type identification is done at runtime, the compiler can't decide what function to call when building the code. The correct code is:

QLineEdit *le = qobject_cast<QLineEdit*>(activeWidget);
if(le) le->paste();
else {
  QPlainTextEdit *pte = qobject_cast<QPlainTextEdit*>(activeWidget);
  if(pte) pte->paste();
  else qFatal("Unknown widget found");
}

QLineEdit *le = qobject_cast<QLineEdit*>(activeWidget);
if(le) le->paste();
else {
  QPlainTextEdit *pte = qobject_cast<QPlainTextEdit*>(activeWidget);
  if(pte) pte->paste();
  else qFatal("Unknown widget found");
}

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Or a simple and brilliant abuse of one of Qt's features:

QMetaObject::invokeMethod(activeWidget, "paste");

QMetaObject::invokeMethod(activeWidget, "paste");

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which makes use of a fact that paste() is a slot in both classes.