From: MustModify <mustmodify@...>
Date: 2010-04-26T23:50:07+09:00
Subject: Re: Defining your own typecaster

> module Kernel
>   def Foo(*objs)
>     Foo.new(objs)
>   end
> end

This is a valid solution to the problem, but I'm wondering why you
want to do type casting. Typically if you're working in Ruby and
you're looking at that kind of declaration, you've come from C# or
Java or something and you just aren't in the groove yet. If you give
us some context, we might be able to give you a better push.

<plug>
I wrote a gem called Valuable ( http://valuable.mustmodify.com/ ) that
implements very simple type casting for instance attributes. It's
useful in situations where like gets and in Rails where your input
often comes in as a string and you don't want to have to worry with
the logic of casting nil.to_i on accident, etc.

class BaseballPlayer
  has_value :hits, :klass => :integer
  has_value :runs, :klass => :integer
  has_value :team
  has_value :phone_number, :klass => PhoneNumber

  def rbi
    (hits / runs.to_f) if hits && runs
  end
end

>> joe = BaseballPlayer.new(:hits => '24', :runs => '12', :team => 'Dragons')

>> joe.phone_number => 1234567890

>> joe.runs
=> 12

>> joe.rbi
=> 0.5

>> joe.runs = nil

>> joe.rbi
=> nil

>> joe.phone_number
=> "(123) 456-7890"

</plug>

----------
Johnathon Wright
Web Application Consultant

http://blog.mustmodify.com/