From: nobu.nokada@...
Date: 2004-01-21T08:20:00+09:00
Subject: Re: enable debugflag in module

Hi,

At Wed, 21 Jan 2004 06:55:01 +0900,
Simon Strandgaard wrote:
> class Object
>     # enable the global debug flag for just a single method
>     def self.debug(*args)

Should be Module's instance method.

>                 #{org}#{arguments}
>                 $stdout.puts("after ##{name}") 

This discards the result of the original method.

And you'd better to check the method already "debugged" to get
rid of infinite recursion.


class Module
  # enable the global debug flag for just a single method
  def debug(*args)
    debug_methods = private_instance_methods(true)
    args.each{|symbol| 
      name = symbol.id2name
      org = "_debug_"+name
      if debug_methods.include?(org)
        $stderr.puts "ERROR: already debugging method: #{name}"
        next
      end
      begin
        meth = instance_method(symbol)
      rescue => e
        $stderr.puts "ERROR: symbol2method failure, " + e.inspect
        next
      end  
      alias_method org, name
      module_eval %{
        def #{name}(*a, &b)
          $stdout.puts("before ##{name}")
          debug, $debug = $debug, true
          result = #{org}(*a, &b)
          $stdout.puts("after ##{name}")
          result
        ensure
          $debug = debug
        end
        private :#{org}
      }
    }
  end
end

class Test
  module A
    def test
      p 42
    end
    debug :test
  end

  include A
  debug :test      # Error and skipped
end

Test.new.test

-- 
Nobu Nakada