Why doesn't Ruby's select return the socket?

Question

I'm trying to use select on STDIN and a TCP socket in Ruby, but for some reason, the value returned from select never seems to match one of the choices; it looks like it's the socket that's being returned, but it doesn't match using == (or equal?). Can anyone tell me why the result returned from select doesn't match the objects I passed in, and what I should be doing differently here?

server = TCPSocket::new("irc.freenode.net", 7000)
server.puts "NICK MyBot"
server.puts "USER #{ENV['USER']} 0 * :My Bot"

# <snip definitions>

while (!$done)
  results = select([server, STDIN], nil, nil)
  if results[0] == STDIN
    puts "Reading from STDIN"
    execute_command
  elsif results[0] == server
    puts "Reading from server"
    receive_data
  else
    puts "Something's wrong... results[0]: #{results[0]}, server: #{server}"
    puts "IDs: results[0]: #{results[0].__id__}, server: #{server.__id__}"
    exit 1
  end
end

Here's what I get when I run this:

Something's wrong... results[0]: #<TCPSocket:0x33c390>, server: #<TCPSocket:0x33c390>
IDs: results[0]: 1695840, server: 1695990

I'm running Ruby version 1.8.6 on Mac OS X.

$ ruby --version
ruby 1.8.6 (2008-03-03 patchlevel 114) [universal-darwin9.0]
$ which ruby
/usr/bin/ruby

Answer 1

Do you get the same results if you use .equal? or .eql?

http://ruby-doc.org/core/classes/Object.html#M000341

== may be overridden by subclasses, but .equal? is not supposed to be. The main question here is actually why the same object, when compared to itself via ==, is returning false. You may need to check out the source or docs of the TCPSocket class.

Answer 2

The fist element of the Array returned by select is an Array of the IO objects that are ready. So you should compare the STDIN and server to results[0][0]. Or better check, if the socket is in the results Array

...
if results[0].include? STDIN
  ...
elsif results[0].include? server 
 ...
...