From: Jano Svitok <jan.svitok@...>
Date: 2007-05-05T06:19:21+09:00
Subject: Re: Playing with Webrick

On 5/4/07, Jano Svitok <jan.svitok@gmail.com> wrote:
> On 5/4/07, El Gato <wmwilson01@gmail.com> wrote:
> > I know this is all possible with Rails, but I'm thinking about creating
> > a little app that uses WEBrick and I'd like to be able to pass instance
> > variables around from WEBrick to my rhtml.  Does anyone know if that's
> > possible?  For example, given this:
> >
> > class Foo < HTTPServlet::ERBHandler
> >   def initialize(server, name = "#{Dir::pwd}/htdocs/foo.rhtml")
> >     @foo = "hello"
> >     super
> >   end
> > end
> >
> > ...
> > server.mount "/foo", Foo
> >
> > How could I do
> > -- foo.rhtml --
> > <html>
> > ...
> > <%= @foo %>
> > ...
> > </html>
> >
> >
> > Thoughts?  Am I way off on even thinking this is possible.  I know
> > webrick references the binding in the erbhandler, could I somehow
> > override it to use my binding instead?
>
> This is code from ERB handler:
>
>       private
>       def evaluate(erb, servlet_request, servlet_response)
>         Module.new.module_eval{
>           meta_vars = servlet_request.meta_vars
>           query = servlet_request.query
>           erb.result(binding)
>         }
>       end
>
> 1. Webrick defines new module and thus new binding for each request,
> so that request do not interfere with each other. If you'd use one
> binding it would work different (whether it's good or not depends on
> your needs)
>
> 2. you can set a variable in a binding using eval, i.e.
> eval("@#{name}=#{value}", binding) or you can set it directly to the
> created module using instance_variable_set("@#{name}", value) just
> before the erb.result line
>
> 3. you can get a list of instance variable names using instance_variables
>
> 4. probably you will want to filter out some of the variables, e.g. @server
>
> Not tested, just ideas to explore ;-)

And I've forgotten:

5. have a look at rails, how they do it... I don't have them installed
now, so I can't tell you where to look, just search for ERB or similar
(IIRC evaluate_locals is the exact method to look for)

J.