From: Hal Fulton <hal9000@...>
Date: 2006-07-26T09:36:17+09:00
Subject: Re: Hash order bug?

Berger, Daniel wrote:
> 
> 
> No, it's just the way hashes behave.  Note that there are ordered hash
> implementations on the RAA:
> 
> http://raa.ruby-lang.org/project/orderedhash/
> 
> You can also use a Struct to get roughly the same effect.

In case anyone tries to refer me to these, I'll point out that
there are *three* reasons I like a hash.

1. It indexes on an arbitrary value, not on an integer like
an array.
2. It consists of explicit pairings of key and value.
3. There is a convenient sybtax for literals:
    {a=>b, c=>d, e=>f}

Note that there are *no* ordered hash solutions that preserve
the third criterion.

Most would require me to do something like:

   oh = OrdHash.new(a,b, c,d, e,f)

or

   oh = OrdHash.new([a,b], [c,d], [e,f])

or something just as bad.

Don't underestimate the importance of a convenient notation!
What if arrays in Ruby were like arrays in C? In C, you can
specify an array literal (barely) when you declare it; that's
about it.


Hal