From: Hal Fulton <hal9000@...>
Date: 2006-07-26T10:18:24+09:00
Subject: Re: Hash order bug?

William James wrote:
> No.  What language has ordered hashes?
> 
> When you say
> a = {:gr => false, :und => false, :det => true, :sta => false, :inv
>   => false}
> you are saying that you want to access the values in this fashion:
> a[:und]
> So the order in which they are stored is irrelevant.
> If you want to access them this way
> a[1]
> then you set them up like this
> [ false, false, true, false, false ]
> 
> If you want to get a sequence of values in a certain order:
> a.values_at( :und, :det, :sta )

Your point is well taken. David Alan Black also argues eloquently
against the concept of an ordered hash.

But to me there is psychological weight in seeing a literal of this form:

    {a=>b, c=>d, e=>f}

There is in fact a syntactic order (which turns out to be meaningless
internally).

> If you want to have your cake and eat it too, you could
> use an association list:
> 
> 
>>>as = [[:foo,22], [:bar,33], [:baz,44]]
> 
> => [[:foo, 22], [:bar, 33], [:baz, 44]]

[snip]

That works fine, but I dislike the ugly syntax.


Hal