Can dictionary values access their keys?

[Axel Straschil]

Hello!

> If I have a simple dictionary, where the value is a class or function,
> is there an interface through which it can discover what its key is?

The key of a value may not be unique, so you can also get a tupe of
keys, like dict(a=1, b=1), the key's of 1 are a and b.

For unique values, I did something like that couple of weeks ago, the
thing you would need is the getKey thing, it's fast, but needs much
memory for big structures becouse I use two dicts.
If speed does not matter:

class ReverseDict(dict):
	def get_keys(self, value):
		keys = []
		for k, v in self.items():
			if v == value: keys.append(k)
		return keys

class UniqueReverseDict(dict):
	"""
	A dictionary that can resolute reverse: A object to a key. Both, the Key and
	the Value must be unique.
	"""
	
	def __init__(self, **kws):
		super(UniqueReverseDict, self).__init__(kws)
		self.__reverse = {}

	def __setitem__(self, k, v):
		super(UniqueReverseDict, self).__setitem__(k, v)
		self.__reverse[v] = k
	
	def __update_reverse(self):
		self.__reverse.clear()
		for k, v in self.items():
			self.__reverse[v] == k
	
	def has_value(self, v):
		return self.__reverse.has_key(v)
	
	def __delitem__(self, k):
		self.__reverse[self[k]]	
		super(UniqueReverseDict, self).__delitem__(k)

	def clear(self):
		self.__reverse.clear()
		super(UniqueReverseDict, self).clear()
		
	def copy(self):
		return UniqueReverseDict(self)
	
	def pop(self, k):
		del self.__reverse[self[k]]
		return self.pop(k)
	
	def popitem(self, **kws): 
		raise 'AxsPy.Misc.Structures.UniqueReverseDict', \
			'NotImplemented'
	
	def setdefault(self, **kws): 
		raise 'AxsPy.Misc.Structures.UniqueReverseDict', \
			'NotImplemented'
	
	def update(self, **kws):
		super(UniqueReverseDict, self).update(**kws)
		self.__update_reverse()
		
	def getKey(self, v): return self.__reverse[v]

Lg,
AXEL
-- 
"Aber naja, ich bin eher der Forentyp." Wolfibolfi's outing in 
http://www.informatik-forum.at/showpost.php?p=206342&postcount=10