From: Adam Prescott <mentionuse@...>
Date: 2011-03-05T03:31:37+09:00
Subject: Re: Semantics of 1.9.2 Set

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On Fri, Mar 4, 2011 at 6:22 PM, Colin Bartlett <colinb2r@googlemail.com>wrote:

> On Tue, Mar 1, 2011 at 4:45 PM, John <john.g.norman@gmail.com> wrote:
> > I'm looking at the doc for the 1.9.2 Set class, which says
> > (http://www.ruby-doc.org/stdlib/libdoc/set/rdoc/classes/Set.html):
> >
> > Since the doc explicitly defines Hash as the underlying store, and
> > since Hash in 1.9.2 observes insertion order (http://ruby-doc.org/core/
> > classes/Hash.html) during enumeration, I wonder if the doc for Set
> > should be changed?
>
> But given the actual documentation of Set, it would be unwise to do
> this: a later implementation of Set might use something other than an
> insertion order preserving Hash.
>
> In short, I think the documentation for Set should remain as it is. Or
> possibly say explicitly that whilst the current implementation of Set
> uses Hash for storage, it should not be assumed that this will always
> be the case.
>
>
I would agree that the documentation should not mention any order, as that's
not what defines a Set, it's just a leftover from an implementation with
Hashes. I don't think it should be stressed that its current implementation
is a Hash, in the documentation, though. If it's included, it definitely
should be pointed out that the implementation with a Hash is not a normative
restriction.

I was hoping someone who had a detailed knowledge of Set and Hash
> would give you an answer. Since I don't qualify on the detailed
> knowledge grounds, I'll try my knowledge of logic, and hope that fits.


I think you responded quite well, for what it's worth. :)

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