From: Marnen Laibow-Koser <marnen@...>
Date: 2010-01-24T12:04:08+09:00
Subject: Re: Writing proper getter in a Ruby way

Benoit Daloze wrote:
[...]
> Now I begin to describe the real code, because abstract examples would 
> be hard.
> Here it is:
> 
> class Variable
>   attr_accessor :name, :proc
>   attr_writer :value
> 
>   # Create a new Variable, with optional name, value and proc
>   def initialize(*args, &proc)
>     args.each do |arg|
>       case arg
>       when Numeric then @value = arg
>       when String, Symbol then @name = arg.to_s
>       else raise ArgumentError, "..."
>       end
>     end
>     @proc = proc
>   end

This seems a strange use case, but in any event, ou should not be doing 
this much class checking.  I suggest a different approach entirely: pass 
a hash to the constructor rather like many Rails functions do.

So:

class Variable
  attr.accessor :name, :proc
  attr.writer :value

  def initialize(options, &proc)
    @name = options[:name] ? options[:name].to_s : nil
    @value = options[:value]
    @proc = proc
  end

> 
>   def value
>     @value or @proc && @proc.call.value
>   end
> 
>   def to_s
>     name || 'unnamed_variable'
>   end
> end

...and these can stay the same.


Best,
--
Marnen Laibow-Koser
http://www.marnen.org
marnen@marnen.org
-- 
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