From: "F. Senault" <fred@...>
Date: 2009-01-22T22:53:22+09:00
Subject: Re: String doesnt auto dup on modification

(Ooops, sorry if this message makes it through in duplicate with a
"strange" from, but I mixed up my "identities" in my newsreader...)

Le Thu, 22 Jan 2009 00:05:58 -0500, RK Sentinel a �crit :

> Tom Cloyd wrote:

>> If this is an utterly dumb question, just ignore it. However, I AM
>> perplexed by this response. Here's why:
> i agree with you.
> 
> I have objects that get a string, process/clean it for printing/display. 
> (That is the whole purpose of centralizing data and behaviour into 
> classes.)

You could also design some "clever" accessors, like this :

class Class
  def attr_duplicator(*members)
    members.each do |m|
      self.class_eval(<<-EOM)
        def #{m}
          @#{m}.dup
        end
        def #{m}=(v)
          @#{m} = v.dup
        end
      EOM
    end
  end
  nil
end

(Could even bail if the writer is passed something else than a string.)

A long winded example :

>> class Blah ; attr_duplicator :blix ; end
=> nil
>> t = Blah.new()
=> #<Blah:0x000000016fce98>

>> z = "abc"
=> "abc"
>> z.__id__
=> 12031220
>> t.blix = z
=> "abc"
>> t.instance_variable_get("@blix").__id__
=> 12015560

>> t.blix.__id__
=> 11609640
>> t.blix.__id__
=> 11604360

>> t.blix << "aaa"
=> "abcaaa"
>> t.blix
=> "abc"

>> a = t.blix
=> "abc"
>> a << "aaa"
=> "abcaaa"
>> t.blix
=> "abc"

As usual, not sure about the performance impact, though, especially if
you manipulate very big string objects...

Fred
-- 
So I open my door to my enemies
And I ask could we wipe the slate clean
But they tell me to please go fuck myself
You know you just can't win                 (Pink Floyd, Lost For Words)