Connecting to a function with arguments

Question

I\'m working on a user interface with PyQt and have finally figured out how to make multiple display options possible (user clicks on a radio button, a signal is saved, and depe

Answer 1

You say:

The interesting thing is that the specified functions (function1 and function2) appear to run even though I get the error message.

Nothing surprising about that -- you're calling one of those functions right here, and passing that function's result (no doubt the None you get error messaged about) to connect -- that's always, in Python, the meaning of

a(b(c))

for any callables b and a: it means "call b with argument c and pass its result as the single argument of a.

Now when you use, instead,

a(lambda: b(c))

you're asking for a 100%-different semantics -- passing as a's single argument a function that, when later called (w/o arguments), will then "call b with argument c".

functools.partial(b, c), by the way, is an arguably more elegant approach then lambda -- but produces exactly the same semantics.

As for why this isn't fixing everything for you -- I don't know: the code you show, amended with lambda, should be fine -- if everything else in the vast amount of code you don't show was absolutely perfect. So I suspect the latter condition doesn't hold. Can you make a simplified-to-the-bone but complete example that exhibits the bug you still observe (once the lambda fix is applied)...?