Basic inheritance question

MartinRinehart at gmail.com MartinRinehart at gmail.com
Sat Jan 5 11:31:15 CET 2008


Working on parser for my language, I see that all classes (Token,
Production, Statement, ...) have one thing in common. They all
maintain start and stop positions in the source text. So it seems
logical to have them all inherit from a base class that defines those,
but this doesn't work:

import tok

class code:
    def __init__( self, start, stop ):
        startLoc = start
        stopLoc = stop

class token(code):
    pass

x = token( tok.Loc(0, 0), tok.Loc(3, 4) )

print x.startLoc.repr(), x.stopLoc.repr()

AttributeError: token instance has no attribute 'startLoc'

1) Is my design thinking good, or hopelessly unPythonic?

2) If it's good, how do you access base class data attributes? (The
doc is rich in method access info, impoverished when it comes to other
attributes.)



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