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

[Aahz]

On Mon, Mar 08, 2004, Skip Montanaro 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.
> 
>     aahz> No, that's not right.  If
> 
>     aahz>     def foo() [w1, w2]: pass
> 
>     aahz> is valid, this must also always be valid:
> 
>     aahz>     def foo() [w2]: pass
> 
> Can you explain why this must be the case?  I agree that coupling between w1
> and w2 should be discouraged (see my ast example).

Principle of least surprise, essentially.  There are already going to be
enough obscure uses for this; let's try to keep the completely whacky out
of it.  You'll have to come up with an awfully convincing use case to
change my mind.
-- 
Aahz (aahz at pythoncraft.com)           <*>         http://www.pythoncraft.com/

"Do not taunt happy fun for loops. Do not change lists you are looping over."
--Remco Gerlich, comp.lang.python