From: "Brian Schröder" <ruby.brian@...>
Date: 2005-10-03T03:21:26+09:00
Subject: Re: Eval and block problems

On 02/10/05, Ryan Leavengood <leavengood@gmail.com> wrote:
> On 10/2/05, Brian Schr�der <ruby.brian@gmail.com> wrote:
> > Please help me to wrap my mind around this. I want to achieve the following:
> [code snipped]
> >
> > and have the block from the dynamically created method foo be
> > evaluated in the binding of the instance of A.
> >
> > I'm sure this is possible, but I've never really grocked eval,
> > instance_eval and class_eval.
>
> Good question! Because by researching the answer I learned you can
> just pass a block to define_method:
>
> class A
>   def initialize(x)
>     @x = x
>   end
>
>   def self.def_me(cmd, &block)
>     define_method(cmd, &block)
>   end
>
>   def_me("foo") do
>     puts "x is #@x"
>   end
> end
>
> A.new(1).foo
> A.new(2).foo
> __END__
>
> But strictly speaking in this case the separate def_me method is
> redundant since you could just call define_method directly.
>
> Ryan
>
>

Thank you ryan, it is incredible how fast there come really good
answers here. Combining your proposal and davids I have the following.
If I could get rid of the additional method, that would be perfect.

class A
  def self.def_me(cmd, &block)
    define_method("__#{cmd}", &block)

    private "__#{cmd}"

    define_method(cmd) do
      puts "Defined method"
      send("__#{cmd}")
    end
  end

  def_me("foo") do
    puts "Here in block"
    puts "self is #{self}"
  end
end

A.new.foo

regards,

Brian

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