A really short demo (I'm short on time ... in Dublin and rushing off to do day No. 2 of a Python course!)

A loop - an anonymous list, and a modulo function that lets us cycle round and round the members of that list

for k in range(12):
  light = ["red","red-an-yellow","green","yellow"][k%4]
  print light

Giving me the English traffic lighht colours:

Dorothy-2: grahamellis$ python tlight
red
red-an-yellow
green
yellow
red
red-an-yellow
green
yellow
red
red-an-yellow
green
yellow
Dorothy-2: grahamellis$

Here in Dublin, they miss out the red-an-yellow - straight from red to green!
(written 2010-04-13)

 Y104 - Python - Lists and Tuples
  [3348] List slices in Python - 2 and 3 values forms, with an uplifting example - (2011-07-06)
  [3257] All possible combinations from a list (Python) or array (Ruby) - (2011-04-23)
  [3181] Beware - a=a+b and a+=b are different - Python - (2011-02-23)
  [3118] Arrays of arrays - or 2D arrays. How to program tables. - (2011-01-02)
  [2996] Copying - duplicating data, or just adding a name? Perl and Python compared - (2010-10-12)
  [2368] Python - fresh examples of all the fundamentals - (2009-08-20)
  [2284] Strings as collections in Python - (2009-07-12)
  [2280] Creating and iterating through Python lists - (2009-07-12)
  [1789] Looking for a value in a list - Python - (2008-09-08)
  [1641] Tektronix 4010 series / Python Tuples - (2008-05-13)
  [1220] for loop - how it works (Perl, PHP, Java, C, etc) - (2007-06-06)
  [955] Python collections - mutable and imutable - (2006-11-29)
  [899] Python - extend v append on a list - (2006-10-20)
  [657] The ternary operator in Python - (2006-03-25)
  [383] Overloading of operators on standard objects in Python - (2005-07-19)

Back to Python - access to variables in the outer scope

Previous and next or Horse's mouth home

Forward to Multiple inheritance in Python - complete working example

Returning multiple values from a function - Lua
Mixins example in Python
Regular Expressions in Python
Multiple inheritance in Python - complete working example
Traffic lights in Python
Python - access to variables in the outer scope
The Multiple Inheritance Conundrum, interfaces and mixins
Melksham in Pictures
Uploading an image, document or pdf via a browser (php)
A simple example - XML from a Ruby program