On Sat, 24 Oct 2009 10:26:27 am Ben Finney wrote: > Steven D'Aprano <st...@pearwood.info> writes: > > On Sat, 24 Oct 2009 06:04:12 am Terry Reedy wrote: > > > fwiw, I think the use case for this is sufficiently rare that it > > > does not need a separate method just for this purpose. > > > > And yet it keeps coming up, again and again... obviously people > > using sets in code think it has a use-case. > > The desire for this may be obvious, but what seems to be lacking is > One Obvious Way to Do It. > > I agree that ‘for x in foo_set: break’ is not an Obvious Way. > > > The lack of get() in sets and frozensets is sounding more and more > > to me like the victory of purity over practicality. > > What would be the input to ‘set.get’?
It wouldn't take any input. > If it's the value, that makes it rather non-obvious; It makes it pointless if it takes the value. If you already have the value, why would you need to retrieve it from the set? > if I already > know about ‘dict.get’ which takes the key, I'm not going to be > thinking about the ‘get’ method if I don't have a key to feed it. > Once I learn it, I'm going to forget it easily, because it's > inconsistent with ‘dict.get’. So I don't think that meets the > “obvious way” criterion. "get" is such a generic term that I don't believe that is a problem. There are already quite a number of get() methods in the 2.6 std lib: $ grep "def get[(]" *.py _abcoll.py: def get(self, key, default=None): ConfigParser.py: def get(self, section, option): ConfigParser.py: def get(self, section, option, raw=False, vars=None): doctest.py: def get(self): mailbox.py: def get(self, key, default=None): os.py: def get(self, key, failobj=None): pickle.py: def get(self, i, pack=struct.pack): Queue.py: def get(self, block=True, timeout=None): shelve.py: def get(self, key, default=None): sre_parse.py: def get(self): threading.py: def get(self): UserDict.py: def get(self, key, failobj=None): UserDict.py: def get(self, key, default=None): weakref.py: def get(self, key, default=None): weakref.py: def get(self, key, default=None): webbrowser.py:def get(using=None): I think you over-estimate the degree of confusion people suffer from similar sounding methods. I don't think people are confused that dict[key] and list[index] have different semantics, and I don't see why dict.get(key[, default]) and set.get() would be any different. But if you don't like get(), spell it differently. There's plenty of opportunity for bike-shedding: getitem() getelement() get_arbitrary_element() peek() etc. > By analogy with ‘list.pop’, the method that takes the “top” item off > the “stack”, I would expect to see ‘list.peek’ and ‘set.peek’, to see > the item without altering the container. You don't need list.peek() because there already is an obvious way to retrieve an item from a list without removing it: list[index]. -- Steven D'Aprano _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
