Proposed PEP for a Conditional Expression

[Michael Chermside]

> SPEC_6: Use condition as index of tuple.
>     The currently legal syntax "x =
> (false_val(),true_val())[cond]" would be used, but now
> short-circuit.

This would seem to me to be a complete non-starter, since it changes the 
behavior of tuples into some wierd version of a lazy list. It would 
completely and fundamentally change things deep in the heart of Python, 
and probably NOT necessarily in a positive way.

> SPEC_7: Use condition as index "of" tuple.
>     The syntax "x = cond of (false_val(),true_val())"
> would be used.

It sounds like what you're trying to invent here is a short-circuiting 
CASE expression, not a conditional expression. That seems out of scope, 
and so I'm inclined to ommit this one. Please, though, let me know if 
I'm misunderstanding you.

-- Michael Chermside