* Martin Drautzburg:
Hello all,When passing parameters to a function, you sometimes need a paramter which can only assume certain values, e.g. def move (direction): ... If direction can only be "up", "down", "left" or "right", you can solve this by passing strings, but this is not quite to the point: - you could pass invalid strings easily - you need to quote thigs, which is a nuisance - the parameter IS REALLY NOT A STRING, but a direction Alternatively you could export such symbols, so when you "import *" you have them available in the caller's namespace. But that forces you to "import *" which pollutes your namespace. What I am really looking for is a way - to be able to call move(up) - having the "up" symbol only in the context of the function call So it should look something like this ... magic, magic ... move(up) ... unmagic, unmagic ... print up This should complain that "up" is not defined during the "print" call, but not when move() is called. And of course there should be as little magic as possible. Any way to achieve this?
>>> def move( direction ): ... print( "move " + str( direction ) ) ... >>> move( "up" ) move up >>> >>> class using_directions: ... up = 42 ... move( up ) ... move 42 >>> up Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'up' is not defined >>> _ Of course it's an abuse of the language. :-) So I wouldn't recommend it, but it's perhaps worth having seen it. Cheers & hth., - Alf PS: I hope this was not a homework question. -- http://mail.python.org/mailman/listinfo/python-list
