Defining “method_called”.. How do I make a hook method which gets called every time any function of a class gets called?

Question

I want to make a hook method which gets called everytime any function of a class gets called. I have tried method_added, but it executes only once at the time of class defin

Answer 1

Take a look at Kernel#set_trace_func. It lets you specify a proc which is invoked whenever an event (such as a method call) occurs. Here's an example:

class Base
  def a
    puts "in method a"
  end

  def b
    puts "in method b"
  end
end

set_trace_func proc { |event, file, line, id, binding, classname|
  # only interested in events of type 'call' (Ruby method calls)
  # see the docs for set_trace_func for other supported event types
  puts "#{classname} #{id} called" if event == 'call'
}

b = Base.new
b.a
b.b

Outputs:

Base a called
in method a
Base b called
in method b