Case expression different in Ruby 1.9?

Question

This is an example code from a book. I assume it's for Ruby 1.8.

    birthyear = 1986
    generation = case birthyear
        when 1946...1963: "Baby boomer"
        when 1964...1976: "Generation X"
        when 1977...2012: "new generation"
        else nil
    end

    puts generation

I ran it on Ruby 1.9, and got this error message:

    Untitled 2.rb:12: syntax error, unexpected ':', expecting keyword_then or ',' or ';' or '\n'
    when 1946...1963: "Baby boomer"
                     ^
Untitled 2.rb:13: syntax error, unexpected keyword_when, expecting $end
    when 1964...1976: "Generation X"

How should I change this?

Answer 1

You can just replace the colons with semi-colons.

Just tested this example:

birthyear = 1986
generation = case birthyear
    when 1946...1963; "Baby boomer"
    when 1964...1976; "Generation X"
    when 1977...2012; "new generation"
    else nil
end

puts generation

The semi-colon works exactly the same as a new line in this context, I think.

Answer 2

This is the correct way to do it:

score = 70
result = case score
   when 0..40 then "Fail"
   when 41..60 then "Pass"
   when 61..70 then "Pass with Merit"
   when 71..100 then "Pass with Distinction"
   else "Invalid Score"
end
puts result

Answer 3

There is a mistake in your puts

puts generation  # not "gemeration"

also try something like this :

score = 70

result = case score
  when 0..40 then "Fail"
  when 41..60 then "Pass"
  when 61..70 then "Pass with Merit"
  when 71..100 then "Pass with Distinction"
  else "Invalid Score"
end

puts result

Answer 4

According to the 3rd edition of the PickAxe, it is intentional.

p 125, Case Expressions :

"Ruby 1.8 allowed you to use a colon character in place of the then keyword. This is no longer supported."

example, with then and no newlines:

birthyear = 1986
generation = case birthyear
  when 1946...1963 then "Baby boomer"
  when 1964...1976 then "Generation X"
  when 1977...2012 then "new generation"
  else nil
end

puts generation

Answer 5

There was a change in the syntax between 1.8.x and 1.9.x where the : is now no longer allowed:

 birthyear = 1986
 generation = case birthyear
   when 1946...1963
     "Baby boomer"
   when 1964...1976
     "Generation X"
   when 1977...2012
     "new generation"
   else
     nil
   end

 puts generation

Technically : has been replaced by then but that's an optional keyword if you use a newline. It's a bit of a hassle to go and track down cases where you've used the old syntax, so hopefully searching for case is close enough.