Question

Two similar scripts are showing very strange behaviours here.

A) The code below is throwing a nil can't be coerced into Fixnum (TypeError):

    score = 0
    ammount = 4

    score += case ammount
      when ammount >= 3; 10
      when ammount < 3; 1
    end

    puts score

B) And this other one is putting 1 into the console log.

    score = 0
    ammount = 4

    score += case ammount
      when ammount >= 3; 10
      else 1
    end

    puts score

I would expect both scripts to output 10 onto the console. Am I wrong? Why?

Answer 1

When given an argument, the case statement checks for object equality (same as calling ===), which can be used with single values or over ranges. In your case, you’re not really checking for equality, but it can be written like this:

score += case
         when amount >= 3 then 10
         when amount < 3 then 1
         end

However, this is pretty verbose for what you’re trying to do (an either/or condition). It’s simpler to use a plain if...else or a ternary statement:

score += amount >= 3 ? 10 : 1