Passing functions as arguments

I know that something very basic is wrong here which I just fail to see. I'd really appreciate if somebody more experienced in Python could point out where I misunderstood things here. I post a simplified version of my code below. To trace back where the problems start, have an eye on the following:

The MainProgram, instanciated as Main = MainProgram(), has a menu (self.menu = Startmenu()) which is an instance of the Menu class. This Menu class has a list of buttons (self.buttons = [...]) - in this case only one. They are an instance of the Button class. I now need to pass the function to be triggered when the button is clicked to that instance of the Button class, so I can actually use it.

I would really be thankful to any more experienced user having a quick glance at it. I'm sure I'm failing to see something very basic. I bet I'm too tired to see it... Had only some 2 hours sleep since there's a baby in the house now :D

My code:

class MainProgram: #Much much more code def __init__(self): #And so much more code here self.menu = StartMenu() class StartMenu: def __init__(self): #Much code which is not important to us here self.buttons = [Button("d_bt_start", (100, 60) , testfunc, "TEST-TEXT")] class Button: def __init__(self, image, pos = (0, 0), path = Paths.path_img , alpha = False, func = None, args = None): self.img_normal = helper.loadImage(path, image + "_normal.jpg", alpha) self.img_hover = helper.loadImage(path, image + "_hover.jpg", alpha) self.image = self.img_normal self.pos = pos self.x = pos[0] self.y = pos[1] self.width = self.x + self.image.get_width() self.height = self.y + self.image.get_height() self.mouseover = 0 self.func = func self.args = args def update(self, (mx, my)): if (mx >= self.x and mx <= self.width and my >= self.y and my <= self.height): if self.mouseover == 0: self.image = self.img_hover self.mouseover = 1 else: if self.mouseover == 1: self.image = self.img_normal self.mouseover = 0 def clicked(self, button): if (mx >= self.x and mx <= self.width and my >= self.y and my <= self.height): if button == 1: self.func(self.args) 

What should happen: The main file creates an instance of the StartMenu class. In the StartMenu class we define one button as an instance of the Button class. That button should trigger the function testfunc(args) upon being clicked. This testfunction is so far just a print of the "TEST-TEXT" argument.

If I pass the function as

testfunc 

then I get the following error Traceback:

Traceback (most recent call last): File "D:\Python27\_RPG DEMO\DEMO\main.py", line 41, in <module> Main = MainProgram() File "D:\Python27\_RPG DEMO\DEMO\main.py", line 21, in __init__ self.menu = menus.StartMenu() File "D:\Python27\_RPG DEMO\DEMO\menus.py", line 11, in __init__ , zztestfile.testfunc, "TESTEST") File "D:\Python27\_RPG DEMO\DEMO\buttons.py", line 7, in __init__ self.img_normal = helper.loadImage(path, image + "_normal.jpg", alpha) File "D:\Python27\_RPG DEMO\DEMO\helper.py", line 13, in loadImage return pygame.image.load(os.path.join(folder, name)).convert_alpha() File "D:\Python27\lib\ntpath.py", line 96, in join assert len(path) > 0 TypeError: object of type 'function' has no len() 

If I pass it as:

testfunc("TEST-TEXT") 

it triggers but then causes the following Traceback:

TEST-TEXT Traceback (most recent call last): File "D:\Python27\_RPG DEMO\DEMO\main.py", line 41, in <module> Main = MainProgram() File "D:\Python27\_RPG DEMO\DEMO\main.py", line 21, in __init__ self.menu = menus.StartMenu() File "D:\Python27\_RPG DEMO\DEMO\menus.py", line 11, in __init__ , testfunc("TEST-TEXT")) File "D:\Python27\_RPG DEMO\DEMO\buttons.py", line 7, in __init__ self.img_normal = helper.loadImage(path, image + "_normal.jpg", alpha) File "D:\Python27\_RPG DEMO\DEMO\helper.py", line 15, in loadImage return pygame.image.load(os.path.join(folder, name)).convert() File "D:\Python27\lib\ntpath.py", line 96, in join assert len(path) > 0 TypeError: object of type 'NoneType' has no len() 

I've gone through a few tutorials so far, but I really can't figure out where I'm misunderstanding them. I'd really appreciate any help in this!