Running the class's base function about penlight

[alerque]

You can use self._base.sayHello(self) to get your expected results, but I strongly recommend not going down that rabbit hole and instead restructuring your classes so you don't need to call anything other than the _init() function from subclasses. You can add hook methods to the base class and then add the additional functionality by defining hooks in the child class instead.

Also note you do not want the self._base:sayHello() syntax here otherwise self will end up being the base class table instead of your current instance.

[distantforest1]

I apologize, I'm still quite new to Lua. How do you mean? Do you mean something like this:

function Person:speak()
  print("Hello world")
  self:sayHello()
end

function Person:sayHello() print("I have no name") end

local George = class(Person)

function George:sayHello()
  print("My name is George")
end

local g = George()
g:speak()

-- result:
-- Hello World
-- My name is George

Or do you mean actually putting something in the _init itself?

[alerque]

Yes. That's not exactly what I started to describe, but my use case is much more complex involving a variable number of hook functions. What you've done there with a stub function in the base class that gets overridden with a useful function is perfectly appropriate ... at least for that MWE.

[distantforest1]

Ok thank you

[Tieske]

from your first example;

local Person = class()
function Person:sayHello() print("Hello world") end

local George = class(Person)
function George:sayHello()
  self.super:sayHello()  -- Pseudo-code to demonstate what I mean <<
  print("My name is George") 
end

local g = George()
g:sayHello()

-- result:
-- Hello World
-- My Name is George

the line g:sayHello() is Lua's syntactic sugar for the real call being g.sayHello(g) (the the table you call on, is injected as the first parameter).

The same applies to the method definition; function George:sayHello() is actually being defined as function George.sayHello(self) (a parameter named self is injected as the first parameter.

What does this have to do with your question then? Look at this line; self.super:sayHello(), the syntactic sugar will be translated into self.super.sayHello(self.super) so instead of the instance (which is self), we're passing self.super (which is the base class). And this is not what you want, since it will not work. That's what @alerque mentioned.

The syntactic sugar is unavailable for the call to the base class, so you'll have to use the full syntax.
So instead of self.super:sayHello() you'll have to use self.super.sayHello(self).

hth.