Defining/declaring constants in Python

[Irmen de Jong]

Sriram Chadalavada wrote:

>       I am currently using raw numerical values and  was wondering if
> there is an equivalent of #define in Python for declaring constants.
>  	 Is there an elegant way of defining constants in Python? Please let
> me know.

First, #define is not declaring constants in C or C++.
It is a preprocessor instruction that tells the compiler to replace
a piece of source code text by another piece.

That aside,
there is no such thing as a preprocessor or constant declarations in Python.
You can just define a bunch of attributes. That's what I do usually,
for example in the constants.py module of my Pyro project:

  RIF_Varargs  = (1<<0)
  RIF_Keywords = (1<<1)
  RIF_Oneway   = (1<<2)
  RIF_VarargsAndKeywords = RIF_Varargs | RIF_Keywords

  DENIED_UNSPECIFIED=0
  DENIED_SERVERTOOBUSY=1
  DENIED_HOSTBLOCKED=2
  DENIED_SECURITY=3

...and so on.

If you need 'constants' in a stricter sense, have a look at
http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/65207


--Irmen