From: "ara.t.howard" <ara.t.howard@...>
Date: 2007-06-06T05:03:09+09:00
Subject: Re: [ANN] prototype-2.0.0


On Jun 5, 2007, at 12:55 PM, Victor Zverok Shepelev wrote:

> From: ara.t.howard [mailto:ara.t.howard@gmail.com]
> Sent: Tuesday, June 05, 2007 6:33 AM
>
>
>> NAME
>>   prototype.rb
>>
>
> Several small questions about the library:
>
> * Does cloned object has some connections with it's prototype (as  
> per Io:
> "prototype is something knowing how to process messages I don't know")
>

yes.  if one does

   clone = Object.prototype{ @a = 42 }.clone

the clone has a #a method from parent and @a instance var if it's own


> * If so, can object's prototype be changed dynamically? (I mean,  
> b.proto =
> c)
>

no.  but they can be extended

   proto = Object.prototype

   proto.prototyping do
     @a = 42

     def a() @a end
   end

> * And what about Io-like "prototype is context for code blocks?":
>
> block = lambda{puts a + b}
>
> block.call #=> undefined local variable or method `a'
>
> p = Prototype.new{
>   @a = 40
>   @b = 2
> }
>
> block.proto = p
>
> bloc.call  #=> 42
>

sortof.

cfp:~ > cat a.rb
require 'prototype'

block = lambda{ puts a + b }

proto = Object.prototype

proto.prototyping do
   a 40
   b 2
   c &block
end

proto.c


cfp:~ > ruby a.rb
42


i think your exact example would be quite easy to impliment

> BTW, Markaby uses complicated hack to "setup context variables, while
> building HTML" - which is very close to the above example.
>

check out prototype.rb impl - it's very clean imho.  nothing is off  
limits - you can have attribute 'id', 'name', 'object_id', etc and  
everything works.


> * Does anybody uses it in real projects? I mean, does prototype-based
> approach in not prototype-based language have proved to be useful? The
> question is not about "throw the library away", but about "who can  
> say, what
> features in library are useful", "who can recommend library for  
> some tasks?"

example

   Config = Object.prototype{
     YAML.load(IO.read('config')).each do |key, value|
       attribute key => value
     end
   }

   p Config.host
   p Config.port

i'm using it in several project where one might instead use a  
singleton.  the advantage prototype gives you is basically that you  
can have a hierarchy of singletons, each inheriting state and  
behavior from it's parent.  i'm currently building a model->view (no  
controller) system for rails called 'magnetic' that hinges upon the  
ability to specify a hierarchy of properties and behavior over those  
properties and also that requires that each set of properties be a  
singleton (for performance reasons) and it's filling that roll  
nicely.  look for a release in the next few weeks.

kind regards.

-a
--
we can deny everything, except that we have the possibility of being  
better. simply reflect on that.
h.h. the 14th dalai lama