From: John Carter <john.carter@...>
Date: 2006-03-28T06:18:18+09:00
Subject: New Optimization idea.

I have a couple of classes like so...

class Foo
   def step1
     @mine = Hash.new
     # Perhaps stuff things into @mine
   end

   def step2
     @mine.each_pair do |key,value|
       # Do stuff
     end
   end
end

Profiling with my "new" profiler shows that I'm creating many many Hash 
objects, probably way more than I need. In fact most of them are empty.

Optimization trick...


class Object
   FROZEN_EMPTY_HASH = Hash.new.freeze
end

class Foo
   @@hash_cache = Hash.new

   def step1
     @mine = @@hash_cache
     # Perhaps stuff things into @mine
     if @mine.empty?
       @mine = FROZEN_EMPTY_HASH
     else
       @@hash_cache = Hash.new
     end
   end

   def step2
     @mine.each_pair do |key,value|
       # Do stuff
     end
   end
end


John Carter                             Phone : (64)(3) 358 6639
Tait Electronics                        Fax   : (64)(3) 359 4632
PO Box 1645 Christchurch                Email : john.carter@tait.co.nz
New Zealand

Carter's Clarification of Murphy's Law.

"Things only ever go right so that they may go more spectacularly wrong later."

From this principle, all of life and physics may be deduced.