From: "Aleksi Niemelä" <zak@...>
Date: 2001-02-08T19:54:00+09:00
Subject: [ruby-talk:10560] Re: Giving a Proc utility methods?

On Thu, 8 Feb 2001, The Other Clemens wrote:

> IMHO: The reason for this behavior is, that the block closure "takes" its
> binding upon its creation time, which in your case is the "main context"
> of the program. 

True.

> This means you would have to define fail() in the global
> scope in order to let the block code see it. The block closure object
> (class Proc) is just a wrapper consisting of the code (i.e. the block)
> and the binding, but it is NOT the scope of the block(-code). 
> 
> Don't know whether you like this solution better:
> 
> class Foo
>   attr :err
> 
>       def initialize (&meth)
>         @err = meth
>       end
> 
>       def fail (msg)
>         puts msg
>       end
>         
>       def throw_err (msg)
>         @err[msg, self]
>       end
> end
> 
> # I want to preserve this closure...
> bar = "testing..."
> 
> # Example showing the callback works
> my_foo = Foo.new {| msg, other | puts msg + bar}
> my_foo.throw_err "Trial 1: "
> 
> # Example of what I *wanted* to do...
> my_foo = Foo.new {| msg, other | other.fail (msg + bar)}
> my_foo.throw_err "Trial 2: "
> 
> 
> Clemens (the other ;-)

Let me reiterate. This runs and is closer to Ben's original idea of
being able to define a method to the proc object itself. Ben will
probably sort out if any of these versions is what he's after.

    - Aleksi

    class Foo
      attr :err

      def initialize (&meth)
        # TRY to add the method?
        def meth.fail (msg)
          puts msg
        end
        @err = meth
      end

      def throw_err (msg)
        @err[@err, msg]    # give "self" as a first param
      end
    end

    # I want to preserve this closure...
    bar = "testing..."

    # Example showing the callback works
    my_foo = Foo.new {|block, msg| puts msg + bar}
    my_foo.throw_err "Trial 1: "

    # Example of what I *wanted* to do...
    my_foo = Foo.new {|block, msg| block.fail msg + bar}
    my_foo.throw_err "Trial 2: "