Enumeration Programming

Why, When

This Implementation is really near to the UML description of <<Enumeration>>. It uses new style class.

Code

 1 # code is public domain
 2 
 3 class Enumeration(object):
 4  
 5  def __new__(cls, arg):
 6  if hasattr(cls, arg):
 7  return getattr(cls,arg)
 8  else:
 9  return object.__new__(cls, arg)
 10  
 11  def __init__(self, name):
 12  self._name = name
 13  setattr(self.__class__, name, self)
 14 
 15  def __str__(self):
 16  return '#%s' % self._name
 17 
 18  def __repr__(self):
 19  return "%s('%s')" % (self.__class__.__name__, self._name)
 20 
 21  def getEnumerationSet(cls):
 22  result = set()
 23  for attr in dir(cls):
 24  attr = getattr(cls, attr)
 25  if isinstance(attr, Enumeration):
 26  result.add(attr)
 27  return result
 28  getEnumerationSet = classmethod(getEnumerationSet)

Example

 1 class PrimaryColorKind(Enumeration):
 2  pass
 3 PrimaryColorKind('Rouge')
 4 PrimaryColorKind('Vert')
 5 PrimaryColorKind('Bleu')
 6 
 7 print PrimaryColorKind.Rouge, PrimaryColorKind.Vert, PrimaryColorKind.Bleu
 8 print PrimaryColorKind.getEnumerationSet()
 9 
 10 class ColorKind(PrimaryColorKind):
 11  pass
 12 ColorKind('Violet')
 13 
 14 
 15 print ColorKind.Rouge, ColorKind.Violet
 16 print ColorKind.getEnumerationSet()
 17 print repr(ColorKind.Rouge), repr(ColorKind.Violet)
 18 assert(ColorKind.Rouge is ColorKind('Rouge'))

output is :

#Rouge #Vert #Bleu
Set([PrimaryColorKind('Vert'), PrimaryColorKind('Rouge'), PrimaryColorKind('Bleu')])
#Rouge #Violet
Set([PrimaryColorKind('Vert'), PrimaryColorKind('Rouge'), ColorKind('Violet'), PrimaryColorKind('Bleu')])
PrimaryColorKind('Rouge') ColorKind('Violet')
mirville Python 79 % python Enumeration.py
#Rouge #Vert #Bleu
Set([PrimaryColorKind('Vert'), PrimaryColorKind('Rouge'), PrimaryColorKind('Bleu')])
#Rouge #Violet
Set([PrimaryColorKind('Vert'), PrimaryColorKind('Rouge'), ColorKind('Violet'), PrimaryColorKind('Bleu')])
PrimaryColorKind('Rouge') ColorKind('Violet')