From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2010-06-11T16:28:57+09:00
Subject: Re: case when and class

2010/6/11 Une Bévue <unbewusst.sein@google.com.invalid>:
> I've found in case / when if the case is about a class :
>
> case my_var.class
> when String then puts my_var
> when Array  then my_var.each {|v| puts v}
> end
>
> doesn't work

case calls the method === on the when object passing the case object
as an argument. So the above is calling:

String.=== (my_var.class)

If you check this:

http://ruby-doc.org/core/classes/Module.html#M001666

it says it returns true if the object is *an instance* of this class.
So you don't have to pass the class, but the object itself:

case my_var
when String then puts my_var
when Array then my_var.each {|v| puts v}
end

irb(main):003:0> def test var
irb(main):004:1> case var
irb(main):005:2> when String then puts var
irb(main):006:2> when Array then var.each {|v| puts v}
irb(main):007:2> end
irb(main):008:1> end
=> nil
irb(main):009:0> test "hello"
hello
=> nil
irb(main):010:0> test [1,2,3]
1
2
3
=> [1, 2, 3]



>  i do have to use :
>
> case my_var.class.to_s
> when 'String' then puts my_var
> when 'Array'  then my_var.each {|v| puts v}
> end

You can also do this, but the above is cleaner.

Jesus.