CODEWITHSUNDEEP
pythonpyqtpyqt4
throwaway17434
throwaway17434

Reputation: 831

PyQt Window construction

Can someone explain to me the difference between the following two code examples? Why is the top one not working? It executes without error, but the window doesn't stay open.

from PyQt4 import QtGui
import sys

app = QtGui.QApplication(sys.argv)
QtGui.QMainWindow().show()
app.exec_()

and:

from PyQt4 import QtGui
import sys

app = QtGui.QApplication(sys.argv)
win = QtGui.QMainWindow()
win.show()
app.exec_()

Upvotes: 1

Views: 242

Answers (1)

ashwinjv
ashwinjv

Reputation: 2967

In QtGui.QMainWindow().show() you are creating an object of QMainWindow and you are showing it. But you do no save that instance of the QMainWindow in your memory. So eventually python's garbage collection deletes that instance and your QMainWindow no longer shows.

In the second code: win = QtGui.QMainWindow() you save the object instance of QMainWindow to win in your memory. Python does not consider that as garbage because it is in use and hence your window stays open

Upvotes: 2

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