-- Beni Cherniavsky <cben@users.sf.net> wrote: Jeff Sandys wrote:
I showed this thread at the SeaPIG meeting and we talked about handling attributes. I pointed out that the dot is an operator and that you can have a space between the dot, and the group didn't believe me until they tried it.
s = "my string" s . split()
['my', 'string']
I think by showing the students that dot is an operator helps them understand what is going on and they might not be so concerned about making the long variable and method dotted chains.
It's important that they realize that the dot is not a pure operator as the rest of Pythons operators: the thing on its right side is not an arbitrary expression but an identifier. So you can't do ``foo . (bar + baz)`` the way you can do ``foo * (bar + baz)``. Showing the equivallence to `getattr()` is a nice way to demonstarte the fact the right argument is not an expression evaluated in the current environment but actually just a string. -- Beni Cherniavsky <cben@users.sf.net>, who can only read email on weekends. There you go making dot (.) a special operator. ;-> It is no more special than plus (+), star (*), or percent (%). As you said objects need to have a __getattr__ method for dot to work just as they need __add__ method for plus to work, __mul__ method for star to work and __mod__ method for percent to work. Both numbers and strings have all three methods. The thing on the left or right is never an arbitrary expression, it is an object that might have the corresponding method for the given operator.
a = 5 a . __mod__(2) 1 b = "aaa %s ccc" b . __mod__("bbb") 'aaa bbb ccc'
I saw where this company, LiveLogix, has an extention of Python that added a "defop" function, that is kind of like a macro pattern language, that allows you to define infix operations. http://logix.livelogix.com/intro.html Thanks, Jeff Sandys ________________________________________________________________ Juno Gift Certificates Give the gift of Internet access this holiday season. http://www.juno.com/give