My .irbrc file

.irbrc.rb

# load libraries
require 'rubygems'
require 'wirble'

# start wirble (with color)
Wirble.init
Wirble.colorize

# which from http://programmingishard.com/code/507
module Kernel
  # which { some_object.some_method() } => <file>:<line>:
  def where_is_this_defined(settings={}, &block)
    settings[:debug] ||= false
    settings[:educated_guess] ||= false
    
    events = []
    
    set_trace_func lambda { |event, file, line, id, binding, classname|
      events << { :event => event, :file => file, :line => line, :id => id, :binding => binding, :classname => classname }
      
      if settings[:debug]
        puts "event => #{event}"
        puts "file => #{file}"
        puts "line => #{line}"
        puts "id => #{id}"
        puts "binding => #{binding}"
        puts "classname => #{classname}"
        puts ''
      end
    }
    yield
    set_trace_func(nil)

    events.each do |event|
      next unless event[:event] == 'call' or (event[:event] == 'return' and event[:classname].included_modules.include?(ActiveRecord::Associations))
      return "#{event[:classname]} received message '#{event[:id]}', Line \##{event[:line]} of #{event[:file]}"
    end
    
    # def self.crazy_custom_finder
    #  return find(:all......)
    # end
    # return unless event == 'call' or (event == 'return' and classname.included_modules.include?(ActiveRecord::Associations))
    # which_file = "Line \##{line} of #{file}"
    if settings[:educated_guess] and events.size > 3
      event = events[-3]
      return "#{event[:classname]} received message '#{event[:id]}', Line \##{event[:line]} of #{event[:file]}"
    end
    
    return 'Unable to determine where method was defined.'
  end
  alias_method :which, :where_is_this_defined
end

# String#to_proc from http://weblog.raganwald.com/2007/10/stringtoproc.html
class String
  unless ''.respond_to?(:to_proc)
    def to_proc &block
      params = []
      expr = self
      sections = expr.split(/\s*->\s*/m)
      if sections.length > 1 then
        eval sections.reverse!.inject { |e, p| "(Proc.new { |#{p.split(/\s/).join(', ')}| #{e} })" }, block && block.binding
      elsif expr.match(/\b_\b/)
        eval "Proc.new { |_| #{expr} }", block && block.binding
      else
        leftSection = expr.match(/^\s*(?:[+*\/%&|\^\.=<>\[]|!=)/m)
        rightSection = expr.match(/[+\-*\/%&|\^\.=<>!]\s*$/m)
        if leftSection || rightSection then
          if (leftSection) then
            params.push('$left')
            expr = '$left' + expr
          end
          if (rightSection) then
            params.push('$right')
            expr = expr + '$right'
          end
        else
          self.gsub(
            /(?:\b[A-Z]|\.[a-zA-Z_$])[a-zA-Z_$\d]*|[a-zA-Z_$][a-zA-Z_$\d]*:|self|arguments|'(?:[^'\\]|\\.)*'|"(?:[^"\\]|\\.)*"/, ''
          ).scan(
            /([a-z_$][a-z_$\d]*)/i
          ) do |v|  
            params.push(v) unless params.include?(v)
          end
        end
        eval "Proc.new { |#{params.join(', ')}| #{expr} }", block && block.binding
      end
    end
  end
end