Depending on a conditions I would like to connect/re-connect a button to a different function.
Let's say I have a button:
myButton = QtGui.QPushButton()
For this example let's say I check if there is an internet connection.
if connected == True:
myButton.clicked.connect(function_A)
elif connected == False:
myButton.clicked.connect(function_B)
First of all I would like to disconnect a button from any function it was already connected before the button is being re-assigned/re-connected to another function (function_A or function_B). Secondly, I have already noticed that after the button is re-connected it takes an extra click for the button to pick up a new function. After the button is re-connected to another function it still attempts to run a previous function - a function to which a button was connected earlier (before a re-connection). Please advice. Thanks in advance!
It appears a widget's .disconnect() method can be used to disconnect a button from a function it it is connected.
myButton.disconnect()
Unfortunately .disconnect() throws an error if a widget is not connected to any function. To get around it I am using Try/Except. But I would rather use a more elegant solution...
try: myButton.clicked.disconnect()
except Exception: pass
If you need to reconnect signals in many places, then you could define a generic utility function like this:
def reconnect(signal, newhandler=None, oldhandler=None):
try:
if oldhandler is not None:
while True:
signal.disconnect(oldhandler)
else:
signal.disconnect()
except TypeError:
pass
if newhandler is not None:
signal.connect(newhandler)
...
if connected:
reconnect(myButton.clicked, function_A)
else:
reconnect(myButton.clicked, function_B)
(NB: the loop is needed for safely disconnecting a specific handler, because it may have been connected multple times, and disconnect(slot)
only removes one connection at a time.).