[Python-Dev] PEP 318 restrictions on elements (original) (raw)

[Python-Dev] PEP 318 - generality of list; restrictions on elements

Fred L. Drake, Jr. fdrake at acm.org
Mon Mar 8 15:45:30 EST 2004

On Monday 08 March 2004 03:05 pm, Skip Montanaro wrote:

Must take a single argument, which itself must be a callable, right?

I wrote:

I'd expect w2() to be passed whatever w1() returns, regardless of whether it's callable. It should raise an exception if it gets something it can't handle.

On Monday 08 March 2004 03:27 pm, Skip Montanaro wrote:

Yes. I was thinking of the case where we wanted it to return something useful which could be bound to the name "foo". I suppose if you've had

And I certainly expect that's the typical case; I was mostly reacting to your use of the word "must" rather than the idea. When I read "must", that tells me someone is going to check that in the mechanism rather than just passing it on.

too much caffeine you could dream up a case where w1() returns an AST based on the original foo and w2() does something with it to cook up a new object, but I suspect that would be pretty rare.

Defining foo to some useful object doesn't imply that it's callable, or that it can't be further transformed in useful ways.

-Fred

-- Fred L. Drake, Jr. PythonLabs at Zope Corporation

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