On Mar 19, 3:36 pm, Wilbert Berendsen <[EMAIL PROTECTED]> wrote:
> Hi,
>
> i am writing a simple parser, that generates tokens. The parser needs to
> maintain some state, because some parts of the file consist of different
> tokens. I thought the object could simply remember its state by assigning
> it's next() method to the method that is currently parsing. When the state
> changes, the called method rebinds next() and the next token will be returned
> by that function. Here's an example, proving that this indeed works.
>
> >>> class A:
>
> ... def a(self):
> ... self.next = self.b
> ... return 1
> ... def b(self):
> ... self.next = self.a
> ... return 2
> ... def __iter__(self):
> ... return self
> ...>>> a=A()
> >>> a.a()
> 1
> >>> a.next()
> 2
> >>> a.next()
> 1
> >>> j=0
> >>> for i in a:
>
> ... j += 1
> ... if j > 10: break # prevent from running endlessly
> ... print i
> ...
> 2
> 1
> 2
> 1
> 2
> 1
> 2
> 1
> 2
> 1
>
>
>
> my question is: is this legal Python? An iterator could save the next() method
> object, and in that case it could stop working.... It works now, because
> apparently the for- construct resolves 'next' each time for the object before
> calling it.
>
> The other solution would be just jumping to the correct method from within the
> next() method. But that gives an extra call...
>
> Met vriendelijke groet,
> Wilbert Berendsen
>
> --http://www.wilbertberendsen.nl/
> "You must be the change you wish to see in the world."
> -- Mahatma Gandi
""""
"You must be the change you wish to see in the world."
-- Mahatma Gandi
""""
JFYI: Mahatma Gandhi (NOT Gandi).
--
http://mail.python.org/mailman/listinfo/python-list
