From: Jonathan Steel <jonathan@...>
Date: 2010-07-24T02:08:04+09:00
Subject: Re: Trace calls in a module

Robert Klemme wrote:
> On 07/23/2010 06:33 PM, Jonathan Steel wrote:
>> How do you do the equivalent of include in a module? I would like to
>> trace all the calls in a module.
> 
> I don't understand this: why is tracing of method calls equivalent to
> module inclusion?

The aren't, just what I'm trying to do (below) requires an include, 
except I want to use it in a module.

> 
>> There is an example for how to do this
>> as a mixin for a class in the pick axe, but how do I do it for a module?
>> Can I get access to the meta class for the module and mix it in there?
> 
> I don't have my pickaxe handy right now.  What does the code do?  It may
> be possible to just exchange a module with the class.
> 
> Kind regards
> 
>   robert

module TraceCalls
  def self.included(klass)
    klass.instance_methods(false).each do |existing_method|
      wrap(klass, existing_method)
    end
    def klass.method_added(method)
      unless @trace_calls_internal
        @trace_calls_internal = true
        TraceCalls.wrap(self, method)
        @trace_calls_internal = false
      end
    end
    def self.wrap(klass, method)
      klass.instance_eval do
        method_object = instance_method(method)
        define_method(method) do |*args, &block|
          puts "==> calling #{method} with #{args.inspect}"
          result = method_object.bind(self).call(*args, &block)
          puts "<== #{method} returned #{result.inspect}"
          result
        end
      end
    end
  end
end
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