From: Regis d'Aubarede <regis.aubarede@...>
Date: 2010-06-03T22:28:46+09:00
Subject: dynamicaly define a method which body can contain yield

Hello,

So i try to define a methode by providing a bloc which can contain a
yield.

I got a  error 'no block given (yield)' on yield execution

Here is my test code :
class B
    def p1 ; puts "p1"; end
    def p2 ; puts "p2 1" ; yield ; puts "p2 2" ; end
    def self.add_tag(name,&blk)
      puts "defined #{name}..."
      define_method(name) do
         instance_eval(&blk)
      end
    end
    def self.add_tag2(name,str_bloc)
      puts "defined2 #{name}..."
      module_eval %{
         def #{name}()
        #{str_bloc}
         end
  }
     end
end

add_tag2 work well, but is not pretty :

> B.add_tag2  "p4"   "puts 'p4 '; p1  ; p2 { puts 'inp2' } ; yield"  
defined2 p4...
=> nil
> b.p4 { puts 'in p4' }
p4
p1
p2 1
inp2
p2 2
in p4
=> nil

add_tag give a Exception if bloc contain a yield:

> B.add_tag("p5") { puts 'p5 '; yield }
defined p5...
=> #<Proc:0x027edcd4@./essai.rb:6>
> b.p5 { puts 'in p5' }
p5
LocalJumpError: no block given
        from (irb):14
        from ./essai.rb:7:in `instance_eval'
        from ./essai.rb:7:in `p5'
        from (irb):15
        from :0

Is there a solution ?
Thank you!

Attachments:
http://www.ruby-forum.com/attachment/4772/essai.rb

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