From: Alan Burch <orotone@...>
Date: 2006-03-11T07:57:47+09:00
Subject: Help me understand why the Ruby block is slower than without

I just wrote my first Ruby script.  I'm an experienced C and perl 
programmer, so please, if it looks too much like these languages and not 
Ruby, let me know.  I've got a 100K word list (Linux dictionary) on my 
Mac and am opening it then looking for any words that are exactly 10 
letters long with no letters repeating ('profligate\n') == 11 is a 
match.  After I wrote my first version I did some playing.  I first saw 
that the array class mixed in enumerable and that I could use the to_a 
call from there, but a quick check using -r profile showed that my 
original call to split was a much quicker way to convert from a string 
to an array.  I then tried putting the File.open in a block and found 
that this was much slower, even if I subtract out the time for the open, 
which I assume is an error in how the profile is counting total time.

Here's the faster version:

f = File.open("./words")
begin
  while f.gets
    if $_.length == 11
      ar = $_.split(//)
      if ar.uniq! == nil
        print "#{ar.to_s}"
      end
    end
  end
rescue EOFError
  f.close
end

And here's the slower block version:

File.open("./words") { |f|
  while f.gets
    if $_.length == 11
      ar = $_.split(//)
      if ar.uniq! == nil
        print "#{ar.to_s}"
      end
    end
  end
}

Again, the words file is just a list of about 100K unique words from the 
dict command or similar on *nix....

Any critique welcome and enlightenment is encouraged.
Thanks!

-- 
Posted via http://www.ruby-forum.com/.