From: "Ara.T.Howard" <ahoward@...>
Date: 2004-06-30T06:37:56+09:00
Subject: Re: [ANN] arrayfields-3.0.0

On Wed, 30 Jun 2004, Joel VanderWerf wrote:

> ---
> module AccessibleIndex
>   def index_accessor(h)
>     h.each do |sym, idx|
>       define_method sym do
>         self[idx]
>       end
>       define_method "#{sym}=" do |val|
>         self[idx] = val
>       end
>     end
>   end
> end
>
> a = [0,1,2,3,4,5]
> class << a
>   extend AccessibleIndex
>   index_accessor :x => 3
> end
>
> a.x = "three"
> p a     # ==> [0, 1, 2, "three", 4, 5]
> ---
>
> But this approach doesn't help with values_at and the like.

cool.  your way is perhaps safer.  ;-)

the reason i wrote this in the first place was that i was doing alot of
postgresql work and it was returning these huge result sets that i would then
write code that looked like:

   if tuple[17] =~ pat or tuple[9].to_i < 42
     ...
   end

and i was reading my own code thinking - huh?  so then i started doing:

   res = pgconn.exec sql

   tuples = res.result
   fields = res.fields

   tuples =
     tuples.collect do |tuple|
       h = {}
       fields.each do |field|
         h[field] = tuple.shift
       end
       h
     end

this is NOT good if tuple.size == 42000!!  finally i wrote the arrayfields
module.  it still requires work:

   res = pgconn.exec sql

   tuples = res.result
   fields = res.fields

   tuples.each{|t| t.fields = fields}


but now all 42000 tuples SHARE a copy of fields for doing their lookups - i
still have to iterate over all of em - but i don't need to create any new
objects and my code new reads like:

   if tuple['name'] =~ pat or tuple['age'].to_i < 42
     ...
   end

which is a lot nicer.

in any case it's just one of those things that i ended up using alot.  i'd
like to re-write it in C but don't have the time right now...


cheers.


-a
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