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 -- http://mail.python.org/mailman/listinfo/python-list
