From: steve <coderrr.contact@...>
Date: 2008-10-30T06:11:31+09:00
Subject: Re: Passing a block with define_method

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here's another way to do it:

    m = instance_method(method_name)

    define_method "__call__#{method_name}" do |b, *a|
      begin
        m.bind(self).call(*a, &b)
      ensure
        p :WRAPPED!
      end
    end

    eval <<-EOF
      def #{method_name} *a, &b
        __call__#{method_name}(b, *a)
      end
    EOF

- steve

On Tue, Aug 26, 2008 at 10:28 PM, ara.t.howard <ara.t.howard@gmail.com>wrote:

>
> On Aug 26, 2008, at 8:30 AM, James Coglan wrote:
>
>  Hi list,
>>
>> I've got a bit of a problem whereby I need to pass a block to a method
>> defined using define_method this works:
>>
>> def some_method(*args, &block)
>>  # ...
>> end
>>
>> but this does not -- the interpreter complains about unexpected
>> ampersands:
>>
>> define_method(:some_method) do |*args, &block|
>>  # ...
>> end
>>
>> Is there any way to make this work? I'm doing something a little meta, so
>> I
>> don't know the name of the method or the number of arguments, so it's all
>> got to be dynamic.
>>
>>
>>
>> --
>> James Coglan
>>
>
>
> a working example:
>
> cfp:~ > cat a.rb
> module Continuations
>  Funcs = {}
>  def Continuations.funcs() Funcs end
>
>  def accepts_continuation *argv
>   argv.flatten.compact.each do |arg|
>     arg = arg.to_s
>     klass = Class === self ? self : self.class
>     Funcs[arg] = klass.send(:instance_method, arg)
>     klass.module_eval <<-code
>       def #{ arg }(*a, &b)
>         Continuations.funcs[#{ arg.inspect }].bind(self).call(*a, &b)
>       ensure
>         STDERR.puts 'wrapped!'
>       end
>     code
>   end
>  end
> end
>
> def foo &b
>  b.call 'bar'
> end
>
> foo{|bar| puts "foo#{ bar }"}
>
> include Continuations
> accepts_continuation :foo
>
> foo{|bar| puts "foo#{ bar }"}
>
>
>
> cfp:~ > ruby a.rb
> foobar
> foobar
> wrapped!
>
>
>
> a @ http://codeforpeople.com/
> --
> we can deny everything, except that we have the possibility of being
> better. simply reflect on that.
> h.h. the 14th dalai lama
>
>
>
>
>

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