TypeError : Method takes exactly 2 arguments (3 given)

Question

Trying to make a program to monitor usb drive connections using pyudev. Here is the code:

def __init__(self):
    self.window = gtk.Window()
    self.window.set_default_size(300, 300)

    self.vbox= gtk.VBox(False, 5)
    label = gtk.Label("Please plug the device")

    context = Context()
    monitor = Monitor.from_netlink(context)
    monitor.filter_by(subsystem='block',device_type='disk')
    observer = GUDevMonitorObserver(monitor)
    observer.connect("device-added",self.device_connected)
    monitor.start()

    self.vbox.pack_start(label)
    self.window.add(self.vbox)

    self.window.show_all()

def device_connected(self, device):
    self.window.remove(self.vbox)
    label = gtk.Label('{0!r} added'.format(device))
    self.vbox.pack_end(label)
    self.window.add(self.vbox)

The traceback :

vineet@vineet:~/Documents/Project$ python project.py
TypeError: device_connected() takes exactly 2 arguments (3 given)
TypeError: device_connected() takes exactly 2 arguments (3 given)

Please help me rectify this.

I am trying to use the piece of code given on the docs page. As you will notice , the device_connected method has the arguments - device_connected(observer,device) but the code doesn't work in that case either. It returns the throws the same error. But I was wondering how it would work in the first place. Shouldn't every method of a class have self as an argument?

score 0 · Answer 1 · answered Mar 16 '14 at 13:28

0

The docs don't say those are methods of the class, but signals that are sent by that class. (In fact the name the docs are using is "device-added", which isn't even a valid function name in Python.)

The function should be a standalone one, which you register as a listener for that signal. You can see in the code snippet at the top of the page an example of how to connect your signal to the observer.

answered Mar 16 '14 at 13:28

Daniel Roseman

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oh yea! But then, how can I make changes to `self.window` if the function is not a part of the class? And if I were to make the function a part of the class how do I resolve the arguments issue? – Flame of udun Mar 16 '14 at 13:34
Also running the program after I make the function a stand-alone one along with pulling the all the monitor related code out of the class throws the error : `observer.connect("device-added",device_connected) NameError: name 'device_connected' is not defined` – Flame of udun Mar 16 '14 at 13:40
Ok the above seems to have been resolved.Placing the method declaration before `observer.connect` does the trick. – Flame of udun Mar 16 '14 at 13:44

TypeError : Method takes exactly 2 arguments (3 given)

1 Answers1