From: Brian Candler <b.candler@...>
Date: 2010-01-26T23:40:34+09:00
Subject: Re: Why is the Binding object so useless?

Tony Arcieri wrote:
> = No really, why do you want to do that?
> 
> I would like to implement a remote REPL with a stateless Ruby server and 
> a
> non-Ruby client

Your proposed feature would also make things like the ActionPack 
template rendering much cleaner. grep for "local_assigns" in 
action_view/renderable.rb (rails 2.3.x) and weep. Here is what they end 
up doing, where local_assigns is a hash of variable=>value bindings:

      def compile!(render_symbol, local_assigns)
        locals_code = local_assigns.keys.map { |key| "#{key} = 
local_assigns[:#{key}];" }.join

        source = <<-end_src
          def #{render_symbol}(local_assigns)
            old_output_buffer = 
output_buffer;#{locals_code};#{compiled_source}
          ensure
            self.output_buffer = old_output_buffer
          end
        end_src

(Rails 3 is the same, but the file is action_view/template.rb and the 
method is compile not compile!)

The above is probably what your REPL server should do.

I guess what you propose wasn't implemented simply because it involves 
work to convert bindings between their internal representation and 
external forms like Hash and Marshal#dump. If you grab an existing live 
binding and pass it around, the conversion isn't required.
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