From: Simon Strandgaard <qj5nd7l02@...>
Date: 2003-11-17T10:23:06+09:00
Subject: Re: overload method in module_eval,  how?

On Mon, 10 Nov 2003 16:43:20 +0100, ts wrote:

>>>>>> "S" == Simon Strandgaard <qj5nd7l02@sneakemail.com> writes:
> 
> S> Still only the first output statement are working.
> S> I don't understand why the successive print-statements doesn't output
> S> anything.  Any hints ?
> 
> 
>  I've given the hint : method is a Symbol, and the method Symbol#arity is
>  not defined.
> 
>  You must first call Kernel#method with the symbol as argument and then
>  call arity
> 
> svg% ruby -e 'def test_x() end; method = :test_x; p method(method).class'
> Method
> svg%
>  
> svg% ruby -e 'def test_x() end; method = :test_x; p method(method).arity'
> 0
> svg%

I think I do symbol2method lookup wrong. How does I lookup
the symbol in the instance namespace ?

--
Simon Strandgaard


server> ruby test_dbg.rb
["test_x"]
symbol = test_x
ERROR: symbol2method failure, #<NameError: undefined method `test_x' for class `Class'>
method = 
method.class = NilClass
Loaded suite test_dbg
Started
..
Finished in 0.002409 seconds.

1 tests, 1 assertions, 0 failures, 0 errors
server> expand -t2 test_dbg.rb 
require 'test/unit'

class Object
  def self.debug(*args)
    p instance_methods(false)
    args.each{|symbol| 
      puts "symbol = #{symbol}"

      begin
        meth = method(symbol)
      rescue => e
        puts "ERROR: symbol2method failure, " + e.inspect
      end
      puts "method = #{meth}"
      puts "method.class = #{meth.class}"
      
      n = meth.arity
      puts "arity=#{n}" 

      name = symbol.id2name
      org = "_debug_"+name
      arguments = (n != 0) ? "(*a,&b)" : "(&b)"
      code=<<MSG
      alias #{org} #{name}
      def #{name}#{arguments}
        $stdout.puts("before")
        #{org}#{arguments}
        $stdout.puts("after") 
      end
      private :#{org}
MSG
      module_eval code
    }
    p instance_methods(false) 
  end
end

class TestDbg < Test::Unit::TestCase
  def test_x
    assert_equal(true, true)
  end
  debug :test_x
end

require 'test/unit/ui/console/testrunner'
Test::Unit::UI::Console::TestRunner.run(TestDbg)
server>