From: Charles Steinman <acharlieblue@...>
Date: 2005-07-04T02:15:44+09:00
Subject: Re: two questions: one for XML Builder, one for ERB.


Greg Chen(China) wrote:
> 1.
>  require_gem 'builder'
>
>
>  builder = Builder::XmlMarkup.new(:target�=>STDOUT, :indent=>2)
>  builder.person { |b| b.name("Jim"); b.phone("555-1234") }
>
>
>  #
>  # Prints:
>  # <person>
>  #   <name>Jim</name>
>  #   <phone>555-1234</phone>
>  # </person>
>
>
> The code is clear, but how to understand "builder.person"? A dynamic
> method?

Yep. Builder uses method_missing to dynamically create markup methods
as they are called.

> 2.
>
>
> require 'erb'
> File.open( ARGV[0] ) { |fh|
> erb = ERB.new( fh.read )
> print erb.result( binding )
>
>
>
> }
>
>
> How to understand "binding"? Where does it defined?

It's defined in the Kernel module. From "ri Kernel.binding":

---------------------------------------------------------
Kernel#binding
     binding -> a_binding
------------------------------------------------------------------------
     Returns a +Binding+ object, describing the variable and method
     bindings at the point of call. This object can be used when
calling
     +eval+ to execute the evaluated command in this environment. Also
     see the description of class +Binding+.

        def getBinding(param)
          return binding
        end
        b = getBinding("hello")
        eval("param", b)   #=> "hello"