On Thu, Sep 29, 2011 at 2:27 AM, Matthew J Tretter <matthew@exanimo.com> wrote:
So has Jan's post-** argument list proposal from June (http://mail.python.org/pipermail/python-ideas/2011-June/010479.html) been definitively nixed? It seemed the perfect answer given that its similarity to the default argument hack makes it intuitive when the evaluation is taking place.
It has in my mind. As Guido noted, default argument *names* refer to ordinary locals, and hence exhibit the same rebinding behaviour as pre-nonlocal closure references (i.e. reassignments don't persist across calls, only mutations do). Since we expressly *don't* want that behaviour, anything directly in the argument list (even after **) would be inappropriate. I'm still mulling over the idea of '@state' either as a keyword in its own right or else as a 'known to the compiler' builtin like super so that the following would work (as several people have suggested): @state(n=0, lock=threading.Lock()) def global_counter(): n += 1 return n The special casing of super() is something that annoys me though, and making 'state' a keyword would be extraordinarily disruptive, so I'm also intrigued by the suggestion of reusing 'nonlocal' for the same purpose: @nonlocal(n=0, lock=threading.Lock()) def global_counter(): n += 1 return n With that spelling, the nonlocal statement would declare references to pre-existing closure variables in an outer scope, while the nonlocal decorator would declare new function state variables, implicitly creating the outer scope without all the boilerplate. I must admit, the 'some kind of decorator' syntax is growing on me, especially the nonlocal variant. Cheers, Nick. -- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia