if(!x) vs if(x==false) in ruby

Question

I don\'t understand the following code:

ruby-1.9.1-p378 > puts \"nil is false\" unless nil
nil is false
 => nil 
ruby-1.9.1-p378 > puts \"nil isn\'t         


        

Answer 1

nil is not equal to false by comparison over == because their semantic content is different (nil is no information, false is a boolean value). However, if you try to evaluate nil in a boolean context, it will be considered False, mostly for convenience' sake and idiomatic compatibility with other languages.

nil == a <=> nil != a <=> false is going to be the case for virtually any value of a except for nil.

So you can only tell that 'nil is not true' and 'nil is nil'. This is as far as ruby goes in its ways.