Nick Coghlan wrote:
postdef x = weakref.ref(obj, def) def report_destruction(obj): print("{} is being destroyed".format(obj))
postdef funcs = [def(i) for i in range(10)] def make_incrementor(i): postdef return def def incrementor(x): return x + i
postdef sorted_list = sorted(original, key=def) def normalise(item): …
That actually looks quite readable to me, and is fairly explicit about what it does:
Sorry, but I think it only looks that way to you because you invented it. To me, all of these look like two completely separate statements: some weird thing starting with "postdef", and then a function definition. It might be slightly better if the subsequent def were indented and made into a suite: postdef x = weakref.ref(obj, def): def report_destruction(obj): print("{} is being destroyed".format(obj)) Now it's very clear that the def is a subordinate clause.
With this variant, I would suggest that any postdef clause be executed *in addition* to the normal name binding. Colliding on dummy names like "func" would then be like colliding on loop variables like "i" - typically harmless, because you don't use the names outside the constructs that define them anyway.
That sounds reasonable. However, if we're binding the name anyway, why not use it in the main clause instead of introducing something weird like a lone 'def'? postdef x = weakref.ref(obj, report_destruction): def report_destruction(obj): print("{} is being destroyed".format(obj)) This makes it even more obvious what's going on. Furthermore, there's no longer any need to restrict ourselves to a single 'def' in the body, or even any need for the defining statement to be a 'def' -- anything that binds a name would do. We've now arrived at something very like PEP 3150, but without the local-namespace idea that was causing all the difficulties. -- Greg