From: Benoit Daloze <eregontp@...>
Date: 2010-07-08T02:01:50+09:00
Subject: Re: Ruby switches

On 7 July 2010 17:18, Martin DeMello <martindemello@gmail.com> wrote:
> class User
>  attr_accessor :banned
>
>  def banned?
>    banned
>  end
>
>  def active?
>    not banned
>  end
> end
>
> class Symbol
>  def ===(other)
>    other.send(self)
>  end
> end
>
> a = User.new
> a.banned = true
>
> case a
> when :banned? ; puts "banned!"
> when :active? ; puts "active!"
> end
>
> a.banned = false
>
> case a
> when :banned? ; puts "banned!"
> when :active? ; puts "active!"
> end
>
> martin
>

Quite cool the Symbol#===,
it made me think to Proc#===

Sadly, Proc need always a method to be created (so &:sym can not be
used directly)
But I found a (convoluted) example to use Proc#===

#encoding: utf-8
alias :ė :lambda

def check(user)
  case user
  when ė(&:banned?)
    puts "Banned !"
  when ė(&:active?)
    puts "This is over-convoluted, but you're fine!"
  end
end

user = User.new
user.banned = true
check user
user.banned = false
check user