raise

raise

raise triggers an exception explicitly, either a new one with a message (raise "something broke") or a specific exception class (raise ArgumentError, "bad input"). Calling raise with no arguments inside a rescue block re-raises the currently caught exception. Methods that detect invalid input or state typically raise rather than silently returning an error value.

Note: Bare raise (no arguments) inside a rescue block re-raises the exception currently being handled, preserving its original details.

Example: raise

def check_age(age)
  raise ArgumentError, "Age cannot be negative" if age < 0
  puts "Age #{age} is valid"
end

begin
  check_age(-5)
rescue ArgumentError => e
  puts "Error: #{e.message}"
end