Ruby: hooks for methods

Question

I want to find a gem or to write a code that implements hooks for methods.

class A
  include SomeModule
  before_hook :meth, lambda { puts 'bla' }

  def meth
    puts 'meth'
  end
end

# A.new.meth => "bla\nmeth\n"

I am using Rails and I know about callbacks and filters but

meth isn't an action
I don't wand to change how I method call

Help me please...

UPDATE

I find a gem for automating this code:

  include ActiveSupport::Callbacks
  define_callbacks :meth_callback

  set_callback :meth_callback, :before do |object|
    # my code
  end

  def meth_with_callback
    run_callbacks(:meth_callback) { meth }
  end

  alias_method_chain :meth, :callback

possible duplicate of [Defining "method_called".. How do I make a hook method which gets called every time any function of a class gets called?](http://stackoverflow.com/questions/3236194/defining-method-called-how-do-i-make-a-hook-method-which-gets-called-every-t) — Peter Brown, Jun 10 '12 at 13:02
@jdoe Yes that's it what I want but isn't there a gem whit this functionality? — Kuraga, Jun 10 '12 at 13:19
@АлександрКуракин - you will get better answers if you go back and accept answers to your previous questions. — Mark Reed, Jun 10 '12 at 13:42
@АлександрКуракин This is too simple task for a gem. It's already a part of Rails. What would any one want to extract it?.. — jdoe, Jun 10 '12 at 13:57
@jdoe, I don't think there's some kind of minimum complexity for gems. Small libraries that do one thing well are a good thing; if ActiveSupport was broken up into small parts, people would be able to use what they actually wanted to use without having to depend on the entire thing. — Matheus Moreira, Jun 10 '12 at 15:05

score 5 · Answer 1 · answered Jun 10 '12 at 13:04

5

You can use ActiveModel::Callbacks

define_model_callbacks :create

def create
  run_callbacks :create do
    # do your thing here
  end
end

You can even write a little helper method to hide this run_callbacks line. It may look like this:

hooked_method :create do
  # do your thing here
end

answered Jun 10 '12 at 13:04

Sergio Tulentsev

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Thank you but caller haven't call something else `meth`... An idea is to use `alias_method` and callbacks (internally). But I want to find a gem... – Kuraga Jun 10 '12 at 13:10
Sorry, What do you mean by "but caller haven't call something else meth" ? – Jesse Wolgamott Jun 10 '12 at 13:12
I'm not sure I understand what you mean. – Sergio Tulentsev Jun 10 '12 at 13:12
Call of `meth` have to do something like `run_callbacks(:callback_name) { meth }`. – Kuraga Jun 10 '12 at 13:15
No, `meth` will do it. Read the snippet again. And provided link also. – Sergio Tulentsev Jun 10 '12 at 13:18
@SergioTulentsev `meth` is called by superclass. It shouldn't know about my `run_callbacks` and `hook_methods`... – Kuraga Jun 10 '12 at 13:23
Who shouldn't know? `meth` or superclass? – Sergio Tulentsev Jun 10 '12 at 13:48

Ruby: hooks for methods

1 Answers1