[Tutor] Enumeration and constant

[Alan Gauld]

> I wander how to setup the enumeration type  
> and constant in Python, 

These concepts do not exist in Python per se.

The convention is to make constant names uppercase:

PI = 3.1415926

Enums are a little more variable in implementation depending 
on what you want to do with them. If you need to iterate over 
them a tuple might be a choice with strings as values. But if 
you need to use them as indices into a list a dictionary might 
be better.(But you could use them as keys into a dictionary 
instead of course!)

Other more sophisticated options include creating classes.
These can implement restricted ranges etc

In practice I rarely find I need enums in Python because the 
wealth of data types (lists, tupoles, sets, dictionaries, classes)
means I rarely need and extra symbolic values. I usually find 
myself using enums in other languages because I don't have 
quite the right data type available and an enum helps fake it.

HTH,

Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld