In article <gt1kb7$jqg$0...@news.t-online.com>, Peter Otten <__pete...@web.de> wrote: > >Here's a trick to find the actual element. I think Raymond Hettinger posted >an implementation of this idea recently, but I can't find it at the moment.
Your code is inverted from Raymond's: http://code.activestate.com/recipes/499299/ class _CaptureEq: 'Object wrapper that remembers "other" for successful equality tests.' def __init__(self, obj): self.obj = obj self.match = None def __eq__(self, other): result = (self.obj == other) if result: self.match = other return result # support hash() or anything else needed by __ contains__ def __getattr__(self, name): return getattr(self.obj, name) def get_equivalent(container, item, default=None): '''Gets the specific container element matched by: "item in container". Useful for retreiving a canonical value equivalent to "item". For example, a caching or interning application may require fetching a single representativ e instance from many possible equivalent instances). >>> get_equivalent(set([1, 2, 3]), 2.0) # 2.0 is equivalent to 2 2 >>> get_equivalent([1, 2, 3], 4, default=0) 0 ''' t = _CaptureEq(item) if t in container: return t.match return default -- Aahz (a...@pythoncraft.com) <*> http://www.pythoncraft.com/ "If you think it's expensive to hire a professional to do the job, wait until you hire an amateur." --Red Adair -- http://mail.python.org/mailman/listinfo/python-list
