Question

I am trying to programmatically create and bind a table of accelerators in wxPython in a loop so that I don’t need to worry about getting and assigning new IDs to each accelerators (and with a view to inhaling the handler list from some external resource, rather than hard-coding them). I also pass in some arguments to the handler via a lambda since a lot of my handlers will be the same but with different parameters (move, zoom, etc).

The class is subclassed from wx.Frame and setup_accelerators() is called during initialisation.

def setup_accelerators(self):

    bindings = [
                  (wx.ACCEL_CTRL,  wx.WXK_UP, self.on_move, 'up'),
                  (wx.ACCEL_CTRL,  wx.WXK_DOWN, self.on_move, 'down'),
                  (wx.ACCEL_CTRL,  wx.WXK_LEFT, self.on_move, 'left'),
                  (wx.ACCEL_CTRL,  wx.WXK_RIGHT, self.on_move, 'right'),
                  ]


    accelEntries = []

    for binding in bindings:
        eventId = wx.NewId()
        accelEntries.append( (binding[0], binding[1], eventId) )

        self.Bind(wx.EVT_MENU, lambda event: binding[2](event, binding[3]), id=eventId)


    accelTable = wx.AcceleratorTable(accelEntries)
    self.SetAcceleratorTable(accelTable)

def on_move(self, e, direction):
    print direction

However, this appears to bind all the accelerators to the last entry, so that Ctrl+Up prints "right", as do all the other three. How to correctly bind multiple handlers in this way?

Answer 1

Got it. the problem was you weren’t passing in your direction as an argument to your lambda (it was only looking at the event argument (and self) because that was all your lambda was defined as accepting) This page gave me the help I needed to get this working (here is a gist):

import wx

class MyForm(wx.Frame):

    #----------------------------------------------------------------------
    def __init__(self):
        wx.Frame.__init__(self, None, wx.ID_ANY, "Programmatic binding of accelerators in wxPython", size=(450,150))

        # Add a panel so it looks the correct on all platforms
        panel = wx.Panel(self, wx.ID_ANY)
        bindings = [
                  (wx.ACCEL_CTRL,  wx.WXK_UP, 'up'),
                  (wx.ACCEL_CTRL,  wx.WXK_DOWN, 'down'),
                  (wx.ACCEL_CTRL,  wx.WXK_LEFT, 'left'),
                  (wx.ACCEL_CTRL,  wx.WXK_RIGHT, 'right'),
                  ]


        accelEntries = []

        for binding in bindings:
            eventId = wx.NewId()
            accelEntries.append( (binding[0], binding[1], eventId) )

            self.Bind(wx.EVT_MENU, lambda evt, temp=binding[2]: self.on_move(evt, temp), id=eventId)

        accelTable  = wx.AcceleratorTable(accelEntries)
        self.SetAcceleratorTable(accelTable )
     #----------------------------------------------------------------------

    def on_move(self, Event, direction):
        print "You pressed CTRL+"+direction

# Run the program
if __name__ == "__main__":
    app = wx.App(False)
    frame = MyForm()
    frame.Show()
    app.MainLoop()

My original answer (which is an acceptable alternate solution) is:

import wx

class MyForm(wx.Frame):

    #----------------------------------------------------------------------
    def __init__(self):
        wx.Frame.__init__(self, None, wx.ID_ANY, "Tutorial", size=(500,500))

        # Add a panel so it looks the correct on all platforms
        panel = wx.Panel(self, wx.ID_ANY)
        bindings = [
                  (wx.ACCEL_CTRL,  wx.WXK_UP, self.on_move_up),
                  (wx.ACCEL_CTRL,  wx.WXK_DOWN, self.on_move_down),
                  (wx.ACCEL_CTRL,  wx.WXK_LEFT, self.on_move_left),
                  (wx.ACCEL_CTRL,  wx.WXK_RIGHT, self.on_move_right),
                  ]


        accelEntries = []

        for binding in bindings:
            eventId = wx.NewId()
            accelEntries.append( (binding[0], binding[1], eventId) )

            self.Bind(wx.EVT_MENU, binding[2], id=eventId)

        accelTable  = wx.AcceleratorTable(accelEntries)
        self.SetAcceleratorTable(accelTable )
     #----------------------------------------------------------------------
    def on_move_up(self, event):
        print "You pressed CTRL+up"
    def on_move_down(self, event):
        print "You pressed CTRL+down"
    def on_move_left(self, event):
        print "You pressed CTRL+left"
    def on_move_right(self, event):
        print "You pressed CTRL+right"

# Run the program
if __name__ == "__main__":
    app = wx.App(False)
    frame = MyForm()
    frame.Show()
    app.MainLoop()