error handling: rescue & raise

handle exception:

ex:

begin

      puts  1/0

rescue

     puts "error"

end

--->  "error"

rescue can for specific exception:

ex:

begin

     puts 1/0

rescue  ZeroDivisionError

     puts "error"

end

rescue for method

ex:

def test

    puts "test"

rescue

    puts "rescue"

end

       

raise

raise exception

ex:

def test

   raise  ArgumentError,  "argument error"

end

the second argument is the message printed

get the exception

ex:

rescue ArgumentError =>  e

e is the exception 

define exception

ex:

class  TestException  <>

end