enumeration.py

#
# enum-like type
# From the Python Cookbook, downloaded from http://code.activestate.com/recipes/67107/
#
import types, string, exceptions

class EnumException(exceptions.Exception):
    pass

class Enumeration:
    def __init__(self, name, enumList):
        self.__doc__ = name
        lookup = { }
        reverseLookup = { }
        i = 0
        uniqueNames = [ ]
        uniqueValues = [ ]
        for x in enumList:
            if type(x) == types.TupleType:
                x, i = x
            if type(x) != types.StringType:
                raise EnumException, "enum name is not a string: " + x
            if type(i) != types.IntType:
                raise EnumException, "enum value is not an integer: " + i
            if x in uniqueNames:
                raise EnumException, "enum name is not unique: " + x
            if i in uniqueValues:
                raise EnumException, "enum value is not unique for " + x
            uniqueNames.append(x)
            uniqueValues.append(i)
            lookup[x] = i
            reverseLookup[i] = x
            i = i + 1
        self.lookup = lookup
        self.reverseLookup = reverseLookup
    def __getattr__(self, attr):
        if not self.lookup.has_key(attr):
            raise AttributeError
        return self.lookup[attr]
    def whatis(self, value):
        return self.reverseLookup[value]