Question

I’m writing a simple clipboard manager in wxpython for fun and profit and I’ve run across a peculiar bug that is causing the same function to be called no matter which menu item is clicked.

The code is here and problem is related to lines 49-56 (the “Clear” item works just fine) – it always calls the last function created.

I tried printing the lambda function being created, the menu item, it’s ID – pretty much everything that I could think of that could have been the source of problem, but I didn’t find any clues.

I’m kinda stuck if I can’t choose menu items so I’d appreciate all and any help.

Answer 1

The value of i is being looked-up in the enclosing scope of CreateHistoryMenu. When the func is called, i equals the last value in the loop. That is why the menu items all call the last function created.

If you add i to the arguments of the lambda with a default value, i will become a local variable in the lambda itself, with a default value which was bound at the time the lambda was defined. This will be the right value for i:

        func = lambda e, i = i: self.ChooseItem(i)