[Python-Dev] Coroutines, generators, function calling (original) (raw)

Andrew Koenig ark at acm.org
Thu Oct 20 01:17:05 CEST 2005

We yield values from inside for loops all over the place, but the yielded value is very rarely just the index value (only 1 of 14 yields) , but something calculated from the index value, so the new syntax would not be useful, unless it was something that provided access to the index item as a variable, like:

yield foo(i) for i in x which barely saves you anything (a colon, a newline, and an indent). (hey wait, isn't that a generator comprehension?

Here's a use case:

def preorder(tree):
    if tree:
        yield tree
        yield from preorder(tree.left)
        yield from preorder(tree.right)

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