On Wed, Oct 19, 2011 at 7:43 PM, Terry Reedy <tjreedy@udel.edu> wrote:
On 10/19/2011 2:44 AM, David Townshend wrote:
Regarding out of order execution: how is pep 3150 any worse than "x = y if z else w"?
A lot of people did not like that version of a conditional expression and argued against it. If it is used to justify other backwards constructs, I like it even less.
I happened to be doing a lot of string formatting today, and it occurred to me that because Python doesn't allow implicit string interpolation, *all* string formatting is based on forward references - we define placeholders in the format strings and only fill them in later during the actual formatting call. PEP 3150 is essentially just about doing that for arbitrary expressions by permitting named placeholders that are filled in from the following suite. I agree that using any parallels with conditional expressions as justification for out of order execution is a terrible idea, though. The chosen syntax was definitely a case of "better than the error prone status quo and not as ugly as the other alternatives proposed" rather than "oh, this is a wonderful way to do it" :P Cheers, Nick. -- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia