From: Chris Eskow <chriseskow@...>
Date: 2006-08-08T12:12:25+09:00
Subject: Re: Extracting instance variables from a block?

Ezra Zygmuntowicz wrote:
> 
> [snip]
> 
> class Web
>    def page(url, &blk)
>      @url = url
>      instance_eval &blk
>    end
> end
> 
> web = Web.new
> 
> web.page '/hello/(\w+)' do |name|
>    @title = 'Hello'
>    @name = "Ernie"
> end
> 
> puts web.inspect
> 
> => #<Web:0x32c998 @title="Hello", @name="Ernie", @url="/hello/(\\w+)">
> 
> -Ezra

Thanks for the suggestion (and the compliment), but the problem with 
that is that for every page you define, the block of code you associate 
it with will be called. So, if you define several pages like so:

web.page('/') { web.render 'home.rhtml' }
web.page('/about') { web.render 'about.rhtml' }
web.page('/hello/(\w+)') { |name| @name = name; web.render 'hello.rhtml' 
}

It will render all three templates at once! But it did get me 
thinking... What if I instance_eval it within Web#run? For example:

class Web
  def initialize
    #...
    @obj = Object.new
    def @obj.b; binding; end
  end

  def render(template)
    #...
    ERB.new(File.read(template)).run(@obj.b)
  end

  def run
    #...
    @obj.instance_eval(&action)
  end
end

That sort of works nice... But you can't pass in the URL parameters (the 
ones that your URL regexps match). Is there some way that you can call a 
Proc object (with parameters), but within the context of a specific 
object's binding?

Chris

-- 
Posted via http://www.ruby-forum.com/.