> hello everyone. i was looking at python docs and i came across this > > letter ::= > lowercase | uppercase > > what does ::= mean?
you must be referring to identifiers and keywords page at http://docs.python.org/ref/identifiers.html take it as meaning, "may expand to." in other words, when you are trying to "parse" the language, meaning taking a look at the construct of a valid Python program with the following substitutions: identifier ::= (letter|"_") (letter | digit | "_")* letter ::= lowercase | uppercase lowercase ::= "a"..."z" uppercase ::= "A"..."Z" digit ::= "0"..."9" identifier expands to exactly one occurrence of (letter or _) followed by zero or more (*) occurrences of (letter or digit or _). so.... a variable such as 'testVar_123' matches the identifier token because it can be broken down in that fashion. for example, 't' is matched by letter -> lowercase -> 't' while 'estVar_123' is matched by zero or more occurrences of (letter or digit or _) --> (letter, letter, letter, letter, letter, letter, _, digit, digit, digit) -> lowercase, lowercase, lowercase, uppercase, lowercase, lowercase, _, '1', '2', '3') --> ('e', 's', 't', 'V', 'a', 'r', '_', '1', '2', '3'). you get the picture. hope this helps! -- wesley - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - "Core Python Programming", Prentice Hall, (c)2006,2001 http://corepython.com wesley.j.chun :: wescpy-at-gmail.com cyberweb.consulting : silicon valley, ca http://cyberwebconsulting.com _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
