PythonGenerators

www-106.ibm.com/developerworks/library/l-pycon.html?t=gr,lnxw06=PyIntro

Does anyone know the rationale behind doing this rather than a 'SmallTalk block' type approach (now that the scoping rules have been fixed in Python). I have included some code to show both approaches (needs Python 2.2) ? IvanM

        from __future__ import generators


        class Node:
           pass


        a=Node()
        a.left=Node()
        a.value='d'
        a.right=Node()
        a.right.left=None
        a.right.right=None
        a.right.value='e'
        a.left.value='b'
        a.left.left=Node()
        a.left.right=Node()
        a.left.left.left=None
        a.left.left.right=None
        a.left.left.value='a'
        a.left.right.left=None
        a.left.right.right=None
        a.left.right.value='c'


        #generator way


        def walk(tree):
            if tree==None: return
            for n in walk(tree.left):
                    yield n
            yield tree.value
            for n in walk(tree.right):
                   yield n


        print 'using generator'
        for n in walk(a):
           print n


        #'smalltalk block' way


        def do(tree,block):
           if tree==None: return
           do(tree.left, block)
           block(tree.value)
           do(tree.right, block)


        def prn(x):
           print x


        print 'using smalltalk block style'
        do(a, prn)