[Tutor] function declaration problems perhaps?

[Tiger12506]

> By the way, this is an important and fundamental subject about
> Python.  When I teach classes on Python, I always need to explain
> Python's execution model, and I always struggle with it.  So,
> anything you can tell me that would help me teach this will be much
> appreciated.
>
> Dave

The way I keep it clear is simple. If python needs the value of the name (it 
has to look it up) then it had better be defined. Otherwise ~ It doesn't 
matter!

Think of it like assignment.
x = 1

Does python need to know the current value of x? No. Then x does not have to 
be previously defined.

f()

Does python need to know the current value of f? Yes. It has to know that f 
is a function, and where the address is, etc.

def f1():
  f()

Does python need to know the current value of f? No. Not until f1 is 
executed.

Does this help? Only one rule to remember. ;-) ~Does python need to know the 
value of _this_ variable?~

JS