[Tutor] Order of functions

[Michael P. Reilly]

Praveen Pathiyil wrote
>         Is the order of functions important in python ?
>         Suppose that i have a class X. If i have functions a, b,c and if =
> 'a' calls 'b', is it necessaruy to define 'b' before 'a' or before 'b' =
> is being called.

The only requirement is that the function (or class) needs to be defined
before it is called.  So:

class Eggs:
  f = Toast()  # Toast is not defined yet but is trying to be called

  def __init__(self):
    pass

def Toast():
  pass

would fail when defining the class since func1 is not defined before it
is called.  But:

def Spam():
  f = Ham()  # does not get executed until Spam is called

def Ham():
  pass
Spam()  # Ham is now defined

Would have no problem since Spam would still be defined but the code is
not called.

There is a similar problem with modules:

----- mod1.py -----
import mod2  # import mod2 before funct1 has been defined

def funct1():
  pass
-------------------

----- mod2.py -----
import mod1  # import mod1 and trying to call funct1, but it isn't defined
print dir(mod1)  # won't show funct1
mod1.funct1()
-------------------

Here, the problem is that import happens before the function definition.

It is not a requirement to put functions into a proper order, but it
is a VERY good idea to.  The order I would suggest is: more complicated
functions go last, functions and classes that use fewer other callables
earlier.  There can always be fun exceptions tho. ;)

Hope I'm coherent enough today. :/
  -Arcege

-- 
+----------------------------------+-----------------------------------+
| Michael P. Reilly                | arcege@speakeasy.net              |