From: Trans <transfire@...>
Date: 2007-09-11T03:30:14+09:00
Subject: Re: #to_b - why isn't this one already in there?



On Sep 10, 11:16 am, Sharon Rosner <cico...@gmail.com> wrote:
> On Sep 8, 5:01 am, "Giles Bowkett" <gil...@gmail.com> wrote:
>
> > everybody knows
>
> > if "false"
>
> > returns true.
>
> class Object
>   def to_bool
>     case self
>     when true, false: self
>     when nil: false
>     else
>       to_i != 0
>     end
>   end
> end
>
> class String
>   TRUE_REGEXP = /^(yes|true|on|t|1|\-1)$/i.freeze
>   FALSE_REGEXP = /^(no|false|off|f|0)$/i.freeze
>
>   def to_bool
>     case self
>     when TRUE_REGEXP: true
>     when FALSE_REGEXP: false
>     else
>       to_i != 0
>     end
>   end
> end

Ah. This is a good example for demonstrating what I meant. To fit into
Ruby convention, only TrueClass, FalseClass and NilClass (and things
like NullClass) should respond to to_bool. The String method should be
#to_b, because it is not a true "Boolean" type.

T.