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Ruby Programming
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Expressions



So far we've been fairly cavalier in our use of expressions in Ruby. After all, a=b+c is pretty standard stuff. You could write a whole heap of Ruby code without reading any of this chapter.

But it wouldn't be as much fun ;-).

One of the first differences with Ruby is that anything that can reasonably return a value does: just about everything is an expression. What does this mean in practice?

Some obvious things include the ability to chain statements together.

a = b = c = 0 0
[ 3, 1, 7, 0 ].sort.reverse [7, 3, 1, 0]

Perhaps less obvious, things that are normally statements in C or Java are expressions in Ruby. For example, the if and case statements both return the value of the last expression executed.

songType = if song.mp3Type == MP3::Jazz
             if song.written < Date.new(1935, 1, 1)
               Song::TradJazz
             else
               Song::Jazz
             end
           else
             Song::Other
           end

 rating = case votesCast           when 0...10    then Rating::SkipThisOne           when 10...50   then Rating::CouldDoBetter           else                Rating::Rave           end

We'll talk more about if and case starting on page 79.
Ruby Programming
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