From: Brian Candler <b.candler@...>
Date: 2009-11-16T19:46:06+09:00
Subject: Re: newbie ..need help with metaprogramming..

> var =":a1"
> 
> t = Testvar.new
> if t.respond_to?("#{var}")
>  p 'test 1- pass'
> end

Here you are testing if your object has a particular method. The method 
name is "a1". You can either pass the string "a1" or the symbol :a1

However you passed the string ":a1" consisting of three characters - 
colon, a, 1.

> if t.instance_variable_set var , 'abc'
>  p 'test 2-pass'
> end

Here you are talking about an instance variable, not a method. The 
instance variable's name is "@a1". You can either pass the string "@a1" 
or the symbol :@a1

> if t.send var , 'def'
>  p 'test 3-pass'
> end

Here you're trying to call a setter method. The method's name is "a1=". 
Again, you can either pass the string "a1=" or the symbol :a1=
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