Class design for parser object

[James Saker]

I've been working on a Python class object for APRS (Automatic Position 
Reporting System - a digital mode used by amateur radio operators) and have 
been going through David Mertz's Text Processing in Python book to help in 
the construction of the parser component of the class.

I was curious if there was a good reference on the most pythonic design of 
parsing objects.  For instance, should one parse raw or formatted data upon 
initialization and return a boolean indicating success/failure, or require 
multiple steps to instantiate then parse and test? Are there generally found 
public methods in parsing objects that would serve as a good model? 

Thanks - 

Jamie