From: Robert Klemme <bob.news@...>
Date: 2005-06-17T17:50:33+09:00
Subject: Re: Unless unless

G�bor SEBESTY�N wrote:
> I have this very simple example:
>
> a = 1
> b = nil
> puts a.nil?
> puts b.nil?
> puts "ok" unless a.nil? and b.nil?
>
> Running it results these:
>
> false
> true
> ok
>
> Why the third answer is ok? Unless false and true => false ..
> Clue?

That's standard logic.  Maybe this helps:

>> a = 1
=> 1
>> b = nil
=> nil
>> puts a.nil?
false
=> nil
>> puts b.nil?
true
=> nil
>> puts "ok" unless a.nil? and b.nil?
ok
=> nil
>> a.nil? and b.nil?
=> false
>> puts "ok" unless false
ok
=> nil
>> puts "ok" if not false
ok
=> nil

Kind regards

    robert