From: David Masover <ninja@...>
Date: 2011-01-27T13:20:35+09:00
Subject: Re: Coercion in Ruby

On Wednesday, January 26, 2011 02:52:12 pm Tony Arcieri wrote:
> Just a small nitpick:
> 
>   if other.is_a? TimeInterval
>     TimeInterval.new(value + other.value)
>   elsif other.is_a? Numeric
>     TimeInterval.new(value + other)
>   else
>     raise TypeError, "#{other.class} can't be coerced into TimeInterval"
>   end
> 
> would probably be better written as:
> 
>   case other
>   when TimeInterval
>     TimeInterval.new(value + other.value)
>   when Numeric
>     TimeInterval.new(value + other)
>   else raise TypeError, "#{other.class} can't be coerced into TimeInterval"
>   end

Or at least:

if other.kind_of? TimeInterval
  ...
elsif other.kind_of? Numeric
  ...

Remember duck typing? I don't care if it is_a Numeric, not really. I can't 
really think of many cases where is_a? makes more sense than kind_of?.