From: Dean Strelau <dstrelau@...>
Date: 2006-06-30T03:59:35+09:00
Subject: Re: << for Hash?

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On 6/29/06, Joel VanderWerf <vjoel@path.berkeley.edu> wrote:

> That doesn't seem to stop Set#<< :
>
> irb(main):001:0> s = Set[1,2,3]
> => #<Set: {1, 2, 3}>
> irb(main):002:0> s << 4
> => #<Set: {1, 2, 3, 4}>



That's because the semantics make sense in the context of Set. Set acts like
an unordered list, not like a Hash. There's certanily some hand-waiving
going on to make << work with the Hash, but as has been shown, that's not
too tough. IMO, appending '5' to a list of numbers {1,2,3,4} makes sense
while appending a key/value pair doesn't.

From the doc: 'Set
<http://www.ruby-doc.org/core/classes/Set.html>implements a collection
of unordered values with no duplicates. This is a
hybrid of Array <http://www.ruby-doc.org/core/classes/Array.html>'s
intuitive inter-operation facilities and
Hash<http://www.ruby-doc.org/core/classes/Hash.html>'s
fast lookup."

|| Dean

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