Forum: Ruby Why can this happen?

Hi, I'm learning Rails and saw a strang thing for me.
Yesterday, I was told by my friend that there is a method named
'redirect_to'. He showed how to use the method like this:

redirect_to :back

So, I wanted to find an Api document of the method on the internet,
and tried to know which class or module owns it at first...

----------------------
$ rails console

irb(main)001:0> controller = ActionController::Base.new
=> #<ActionController::Base:0x00000004561ab8 @_routes=nil,
@_action_has_layout=true, @_headers={"Content-Type"=>"text/html"},
@_status=200, @_request=nil, @_response=nil>

irb(main):003:0> controller.method(:redirect_to).owner
=> ActionController::Instrumentation
-------------------------

So I searched 'redirect_to' at http://api.rubyonrails.org/ by using
keyword "ActionController::Instrumentation".

But the document says almost nothing but just the method signeture and
its source code.
--------------------------------------
redirect_to(*args)

# File actionpack/lib/action_controller/metal/instrumentation.rb, line 
58
def redirect_to(*args)

ActiveSupport::Notifications.instrument("redirect_to.action_controller")
do |payload|
    result = super
    payload[:status]   = response.status
    payload[:location] = response.location
    result
  end
end
-------------------------------------

I tried the same search by Google, then I found
the same name method in another module and realized that it was what my
friend told me, because it explained the meaning of 'redirect_to :back'.

http://api.rubyonrails.org/classes/ActionControlle...

But why did I fail to search such a simple thing like this?
Something must have been wrong. I'm very confused.
Was the way of checking class(or method) through irb wrong?

Please give me some advice.

Regards.

i guess somthing went wrong over there.. as i also just checked and got
same as expected

>> controller.method(:redirect_to).owner
=> ActionController::Base

(2013/02/01 17:56), Shridhar Agarwal wrote:
> i guess somthing went wrong over there.. as i also just checked and got
> same as expected
>> controller.method(:redirect_to).owner
>=> ActionController::Base

What!?

How about the version of Ruby and Rails?
-------------------
mine are as bellow....

$ rails -v
Rails 3.2.8

$ ruby -v
ruby 1.9.3p125 (2012-02-16 revision 34643) [x86_64-linux]
-------------------

And I checked again, but the result wan't changed.
----------------------------------
$ rails console
...
...
Loading development environment (Rails 3.2.8)
irb(main):001:0> controller = ActionController::Base.new
=> #<ActionController::Base:0x0000000460e600 @_routes=nil,
@_action_has_layout=true, @_headers={"Content-Type"=>"text/html"},
@_status=200, @_request=nil, @_response=nil>
irb(main):002:0> controller.method(:redirect_to).owner
=> ActionController::Instrumentation