From: Jeremy Wells <jwells@...>
Date: 2006-12-09T01:12:14+09:00
Subject: Re: insert into erb binding

Ah ok, I get it but here is the problem, which I didn't specify... 
@variable2 doesn't hold static data, it holds an object, which is 
created in the render method like so:

def render
    @variable2 = Object.new
    eval("@variable2 = ????", @binding)

That's what I meant by the variable not being in the binding, thus not 
accessible to eval.

Jan Svitok wrote:
> On 12/8/06, Jeremy Wells <jwells@servalsystems.co.uk> wrote:
>> surely this won't work as the binding in my case is coming from an
>> external source, so the ruby in the eval won't have access to the
>> variable in the render method?
>
> So once more: The trick is to use eval with binding as an additional 
> argument.
> That means when eval gets a binding as the second argument, it will 
> operate
> in that context. In this case, if you eval("@var = 123",
> some_binding), the variable @var will be set in that binding.
>
> Beware that you are modifying the original binding, so you might
> corrupt the original caller.
> Maybe @binding = apply_binding.dup will be neccessary.
>
> (I added @ in the template - it was missing)
>
> require 'erb'
>
> # TEMPLATE = "<xml><%=@variable1%> <%=variable2%></xml>"
> TEMPLATE = "<xml><%=@variable1%> <%=@variable2%></xml>"
>
> class Renderer
>    def initialize(template_file, apply_binding)
>       @file = template_file
>       @binding = apply_binding
>    end
>
>    def render
>        # @variable2 = "There"
>        eval("@variable2 = \"There\"", @binding)
>
>        # template = ERB.new(File.read(@file))
>        template = ERB.new(TEMPLATE)
>
>        template_results = template.result(@binding)
>
>        # Perform on template results
>
>     template_results
>    end
> end
>
> require 'test/unit'
>
> class TestERB < Test::Unit::TestCase
>     def test_variable
>         @variable1 = "Hello"
>
>         renderer = Renderer.new('template.xml', binding)
>         assert_equal "<xml>Hello There</xml>", renderer.render
>     end
>
> end
>

-- 

 
*Jeremy Wells*
Serval Systems Ltd.

www.servalsystems.co.uk <http://www.servalsystems.co.uk>
Tel: 01342 331940
Fax: 01342 331950