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One property of the Ruby object model and object oriented programming in general is that a subclass of an object automatically inherits all of the methods of its superclass. Classes can further expand the number of methods available by mixing in a Module, or several.

Because of mixins and subclassing even a class that has declared just a few methods can actually have hundreds of methods on it. In Ruby, all classes subclass Object by default which declares a hefty 45 methods, guaranteeing you to have at least that many. Out of the box in 1.8.7, a Ruby String object has 176 instance methods. If you are programming on top of the Rails framework, ActiveSupport adds 98 methods bringing the total to 274!

On numerous occasions I have needed to see what methods are available on an object I am working with I will type the following in irb.

myobject.methods - Object.instance_methods

This prints out a large array of instance methods with the methods inherited from Object removed from the list. This is useful but what if the object I am working with mixed in several modules and I am left with a list of over a hundred methods? It would be great to view which Class or Module each method came from. Well, actually there's a gem for that.™
Looksee

Looksee is a new gem by George Ogata that examines the method lookup path of any object. To use it add require 'looksee/shortcuts' to your ~/.irbrc. This will add a lp ("lookup path") method to your irb environment. When passed an object lp prints out a colored display showing where each of an object's methods lives.

• public methods are show in green
• protected methods are show in yellow
• private methods are show in red
• overwritten methods are show in gray

Go ahead and install Looksee and play around with it for a moment. Run lp on a String in vanilla irb and then open script/console in a Rails project and do the same thing. It is quite eye-opening to see the additions that the Rails framework makes.

bringout@nmraka-2:~$ cat ~/.irbrc

require 'rubygems'
require 'looksee/shortcuts'

prije toga:

bringout@nmraka-2:~$ sudo gem install oggy-looksee

irb(main):004:0> a=[1,"a",[2,3]]
irb(main):006:0> lp a

=> Array
  &         combination  fetch       last         reverse!      take_while     
  *         compact      fill        length       reverse_each  to_a           
  +         compact!     find_index  map          rindex        to_ary         
  -         concat       first       map!         select        to_s           
  <<        count        flatten     nitems       shift         to_yaml        
  <=>       cycle        flatten!    pack         shuffle       transpose      
  ==        delete       frozen?     permutation  shuffle!      uniq           
  []        delete_at    hash        pop          size          uniq!          
  []=       delete_if    include?    product      slice         unshift        
  assoc     drop         index       push         slice!        values_at      
  at        drop_while   indexes     rassoc       sort          yaml_initialize
  choice    each         indices     reject       sort!         zip            
  clear     each_index   insert      reject!      taguri        |              
  collect   empty?       inspect     replace      taguri=     
  collect!  eql?         join        reverse      take        
Enumerable
  all?        each_cons        find_all    max        one?          take      
  any?        each_slice       find_index  max_by     partition     take_while
  collect     each_with_index  first       member?    reduce        to_a      
  count       entries          grep        min        reject        zip       
  cycle       enum_cons        group_by    min_by     reverse_each
  detect      enum_slice       include?    minmax     select      
  drop        enum_with_index  inject      minmax_by  sort        
  drop_while  find             map         none?      sort_by     
Object
  dump_lookup_path  taguri   to_yaml             to_yaml_style
  lookup_path       taguri=  to_yaml_properties
Kernel
  ==        extend                      instance_variables  singleton_methods
  ===       freeze                      is_a?               taint            
  =~        frozen?                     kind_of?            tainted?         
  __id__    hash                        method              tap              
  __send__  id                          methods             to_a             
  class     inspect                     nil?                to_enum          
  clone     instance_eval               object_id           to_s             
  display   instance_exec               private_methods     type             
  dup       instance_of?                protected_methods   untaint          
  enum_for  instance_variable_defined?  public_methods    
  eql?      instance_variable_get       respond_to?       
  equal?    instance_variable_set       send