From: 7stud -- <bbxx789_05ss@...>
Date: 2009-05-11T08:55:38+09:00
Subject: Re: Adding data to text file variables

7stud -- wrote:
>
> template = ERB.new(file_contents)
> name, clothing, adj = "Diane", "dress", "lovely"
> 
> new_contents = template.result
> puts new_contents
> 
> --output:--
> 
> The result method looks for the variables name, clothing, and adj in the 
> current scope.

Uhmm...not quite.  The result method actually looks for the name, 
clothing, and adj variables in the "toplevel" scope, i.e. the global 
scope.  Look at this example:

require 'erb'

def replace(str)
  name, clothing, adj = "Joe", "hat", "chilly"
  template = ERB.new(str)

  new_contents = template.result
end

name, clothing, adj = "Diane", "dress", "lovely"

file_contents =<<ENDOFSTRING
Hello there <%= name %>.  I see
that you are wearing a new <%= clothing %>.
That looks good on you.  What a <%= adj %>
day it is today.  Goodbye.
ENDOFSTRING

puts replace(file_contents)

--output:--
Hello there Diane.  I see
that you are wearing a new dress.
That looks good on you.  What a lovely
day it is today.  Goodbye.

The result method did not see the the local variables name, clothing, 
adj because by default it is programmed to look in the toplevel scope.

However, result takes an argument that specifies what scope result 
should look in for the values of the variables specified in the 
template.  And the Kernel method "binding" can be called to return the 
surrounding scope.  As a result, you can do this:

require 'erb'

def replace(str)
  name, clothing, adj = "Joe", "hat", "chilly"
  template = ERB.new(str)

  new_contents = template.result(binding)
end

name, clothing, adj = "Diane", "dress", "lovely"

file_contents =<<ENDOFSTRING
Hello there <%= name %>.  I see
that you are wearing a new <%= clothing %>.
That looks good on you.  What a <%= adj %>
day it is today.  Goodbye.
ENDOFSTRING

puts replace(file_contents)

--output:--
Hello there Joe.  I see
that you are wearing a new hat.
That looks good on you.  What a chilly
day it is today.  Goodbye.


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