throw and catch example

throw_and_catch.rb

# catch executes its block.
# If a throw is executed, Ruby searches up its stack for a catch block with a tag corresponding to the throw's tag.
# If found, that block is terminated, and catch returns the value given to throw.
# If throw is not called, the block terminates normally, and the value of catch is the value of the last expression evaluated.
# catch expressions may be nested, and the throw call need not be in lexical scope.

def routine(n)
  puts n
  throw :done, "I'm the return value" if n <= 0
  routine(n-1)
end

catch(:done) { routine(3) }
# 3
# 2
# 1
# 0
# => "I'm the return value"