Is there a python construct that is a dummy function?

Question

Is there a python construct corresponding to a function taking no arguments, doing nothing and not returning anything? Something similar to a None object, but will it be a function instead of an object?

Context

I want to define a class in which the constructor receives the function as an argument and refers to the class attribute. After the expiration, the user decides whether he wants this function to be the actual function that he defines, or to leave the default value, which should call a dummy function that does nothing.

Here is what I have now:

 def sayHello(): print("hello world !") def doNothing(): pass class myClass: def __init__(self, myFunc): self.doIt = myFunc myInstance = myClass(sayHello) myInstance.doIt() myInstance = myClass(doNothing) # Works but requires defining function doNothing() myInstance.doIt() #myInstance = myClass(None) # Returns error "'NoneType' object is not callable" myInstance.doIt() 

Answer 1

How about lambda?

 myInstance = myClass(lambda:None) 

Of course, you can pass your __init__ function by default:

 class myClass: def __init__(self, myFunc = lambda:None): self.doIt = myFunc 

Answer 2

This should work:

 class myClass: def __init__(self, myFunc = lambda : None): self.doIt = myFunc myInstance = myClass() 

Answer 3

This worked for me:

def none(function=True): if function==True: return None else: function()

Answer 4

I used the following:

 a=lambda:None a() print a() 

The last line prints No.