From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-06-14T17:22:40+09:00
Subject: Re: Metaprograming

On Mon, Jun 14, 2010 at 7:23 AM, Sateesh Kambhamapati
<sateesh.mca09@gmail.com> wrote:
> Jesús Gabriel y Galán wrote:
>> On Thu, Jun 10, 2010 at 11:53 AM, Sateesh Kambhamapati
>> <sateesh.mca09@gmail.com> wrote:
>>> end
>>> end
>>> f=flower.new
>>> f.rose-------------------->It gives me rose
>>> but now f.jasmine------------------->It calls method_missing
>>> but i want it comes to my class "Flower"
>>
>> I'm not sure if I understand you correctly, but if you want those
>> method missing calls, to be called on the Flower class, you can do
>> this:
>>
>> irb(main):001:0> class Flower
>> irb(main):002:1> def self.jasmine
>> irb(main):003:2> "jasmine"
>> irb(main):004:2> end
>> irb(main):005:1> def method_missing meth, *args, &blk
>> irb(main):006:2> self.class.send meth, *args, &blk
>> irb(main):007:2> end
>> irb(main):008:1> end
>> => nil
>> irb(main):016:0> Flower.new.jasmine
>> => "jasmine"
>>
>>> So i Want to know which methods are invoked by my "Flower" object
>>
>> I don't understand this question.
>>
>> Jesus.
>
> Thanks for reply
> i would like to know which methods are called by class object i.e
> class Flower
>     def jasmine
>     puts "iam jasmine"
>   end
>      def rose
>      puts "iam rose"
>  end
> end
>
> flowerlist=Flower.new #----->Creating instance for flower
> flowerlist.jasmine  #------->"gives output as "iam jasmine"
> flowerlist.rose  # =======> "gives output as "i am rose"
> flowerlist.lotus   #------->"Shows No Method Error"
>
> Question : --> My Question is i would like to know which methods are
> called by object i.e flowerlist  in the class Flower
>
> if i already know those methods then
> suppose if i have not define some method then i will define it
> dynamically example here is "lotus"
>
> i think u understand my question

As I understand the question now, I think the answer from Phrogz is
spot on. You need to use the method_missing method, which will catch
any call to a method you haven't defined:

class Flower
  def jasmine
    puts "iam jasmine"
  end
  def rose
    puts "iam rose"
  end

  def method_missing meth, *args, &blk
    puts "method #{meth} called, but not defined"
  end
end

flowerlist=Flower.new #----->Creating instance for flower
flowerlist.jasmine  #------->"gives output as "iam jasmine"
flowerlist.rose  # =======> "gives output as "i am rose"
flowerlist.lotus   #=> "method lotus called, but not defined"

So, now you know where you have a place to do whatever you want to do
with a call to a method that doesn't exist. For example, if you want
to dynamically create a method that returns its name as a string, you
can do:

  def method_missing method, *args, &blk
    self.class.send(:define_method, method) do
      method.to_s
    end
    send(method)
  end

This will dynamically define (and call) a method that returns its name
as a string. So if you add that to the Flower class:

class Flower
  def method_missing method, *args, &blk
    self.class.send(:define_method, method) do
      method.to_s
    end
    send(method)
  end
end

f = Flower.new
f.lotus #=> "lotus"
f.rose #=> "rose"

and so on. In any case, I recommend looking at Phrogz's answer,
because it's a nice little utility to automatically define method that
do different things depending the the name patterns.

Regards,

Jesus.