From: Ryan Davis <ryand-ruby@...>
Date: 2010-10-15T06:32:54+09:00
Subject: Re: <Class info> from a String.


On Oct 14, 2010, at 11:03 , Huw Taylor wrote:

> If I were to have this:
> 
> class Hew
>  def initialize(string)
>    @string = string
>  end
>  def other_method
>  end
> end
> 
> a = Hew.new("Broown Cew")
> => #<Hew:0x40e8238 @string = "Broown Cew">
> 
> b = a.to_s
> => "#<Hew:0x40e8238>"
> 
> My question is: Is there anyway to get the class (and its info) from b
> (i.e what is now a string)?
> 
> I see that changing it to a string loses the @string = "Broown Cew" bit.
> :/

There are two potential questions hidden in this problem:

Q1) How do I make the string representation of my object more readable?
A1) Define your own #to_s:

class Hew
 def initialize(string)
   @string = string
 end

 def to_s
   "Hew new #{@string}"
 end
end

cew = Hew.new("Broown Cew")

p cew
# => #<Hew:0x1001560c0 @string="Broown Cew">
puts cew
# => Hew new Broown Cew

Q2) How do I get an object back from a string representation?
A2) Don't use to_s to get a string representation, use YAML, JSON, Marshal, or something else equally suited to serialize and deserialize your object into a readable presentation:

require 'yaml'
s = cew.to_yaml
puts s
# =>
# --- !ruby/object:Hew
# string: Broown Cew
p YAML.load(s)
# => #<Hew:0x1004aa848 @string="Broown Cew">