[Python-Dev] Retrieve an arbitrary element from a set without removing it (original) (raw)

Ben Finney ben+python at benfinney.id.au
Sat Oct 24 01:26:27 CEST 2009

Steven D'Aprano <steve at 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’?

If it's the value, that makes it rather non-obvious; 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.

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.

-- \ “Odious ideas are not entitled to hide from criticism behind | `\ the human shield of their believers' feelings.” —Richard | o_) Stallman | Ben Finney

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