I like to announce a tiny utility I did for my last project. It is only a single class that basically works like LRUCache internally but on the outside it is more like a dictionary. And it has no factory block. If you don't know LRUCache, it's a fixed size dictionary that sorts its elements by usage in a "Least Recently Used" fashion. Meaning the last used element is put in front and the least used at the end. Elements get discarded at the end if space is full. Apart from #at: that is provided by LRUCache , LRUDictionary implements to following methods at:ifAbsent: at:ifAbsentPut: at:ifPresent: at:put: removeAt: removeKey: removeKey:ifAbsent It is available here MCHttpRepository location: 'http://source.selfish.org/mc/misc' user: '' password: '' Blog article is here http://norbert.hartl.name/blog/lrudictionary/ hope you like it, Norbert