On Mon, Jul 13, 2015 at 9:22 PM, Jussi Piitulainen <jpiit...@ling.helsinki.fi> wrote: > That's oddly restricted to self-calls. To get the real thing, "recur" > should replace "return" - I'm tempted to spell it "recurn" - so the > definition would look like this: > > def factorial(n, acc=1): > if n == 0: > return acc > else: > recur factorial(n-1, acc=(acc*n)) > > Probably it would still be syntactically restricted to calls
Huh. Now it looks like the 'exec' operation (the C function and shell operation, not the Python keyword/function) - it's saying "replace the current stack frame with _this_", which looks reasonable. It doesn't have to be recursion. The thing is, you would have to use this ONLY when you don't care about the current stack frame; so you could do a logging decorator thus: def log_calls(func): @functools.wraps(func) def wrapped(*a, **kw): logging.debug("Calling %s(%r, %r)", func.__name__, a, kw) recur func, a, kw return wrapped When an exception occurs inside the wrapped function, the wrapper won't be visible - but that's not a problem, because it doesn't affect anything. Like every other tool, it would be something that could easily be abused, but this actually does justify the removal. It would almost certainly need to be language syntax. I've done it up as a keyword that takes "function, args, kwargs" rather than a prefix on a function call, which emphasizes that the part after it is NOT an expression. In a sense, it makes a counterpart to lambda - where lambda takes an expression and turns it into a function, recur takes a function and treats it as if its body were part of the current function. Kinda. Does that make sense to anyone else? ChrisA -- https://mail.python.org/mailman/listinfo/python-list