Raise Exception

raise reports invalid input from a method, and callers can rescue that error.

raise_exception.rb

def seats_for(requested)
  raise ArgumentError, "too small" if requested < 1
  raise ArgumentError, "too large" if requested > 6

  requested
end

requested = 

begin
  seats = seats_for(requested)
  puts "seats=#{seats}"
rescue ArgumentError => error
  puts "error=#{error.message}"
end

def seats_for(requested)
  raise ArgumentError, "too small" if requested < 1
  raise ArgumentError, "too large" if requested > 6

  requested
end

requested = 

begin
  seats = seats_for(requested)
  puts "seats=#{seats}"
rescue ArgumentError => error
  puts "error=#{error.message}"
end

def seats_for(requested)
  raise ArgumentError, "too small" if requested < 1
  raise ArgumentError, "too large" if requested > 6

  requested
end

requested = 

begin
  seats = seats_for(requested)
  puts "seats=#{seats}"
rescue ArgumentError => error
  puts "error=#{error.message}"
end

raise `raise` creates an exception when a method cannot safely continue.