Erik Groeneveld wrote:
By "closing the delegating generator" you mean "from the outside, call close() on it"?
Yes, that's right.
I assume that 'return 1 2 3' will have one return value being a tuple (1,2,3)
Um, you can't write 'return 1 2 3'. You can write 'return 1, 2, 3' which returns a tuple.
For convenience, the ``StopIteration`` exception will be given a ``value`` attribute that holds its first argument, or None if there are no arguments.
I am using StopIteration's 'args' atrribute?
The 'value' attribute is purely a convenience -- you can get it from args[0] just as well.
For clearity, you could probably add the name of the refactoring, it is called 'extract method' isn't it?
Quite likely it's called that in some book or other, I wouldn't really know. I don't think of refactorings as having names, I just do them.
Yes, I believe you make sure that:
try: x = yield from y() except SomeError: return 'HELP'
actually does catch the SomeError exception when raised in y(), or one it its descendants?
That's the idea.
Originally it was proposed to simply extend StopIteration to accept a value...
That whole paragraph shouldn't be there, it's left over from an earlier version. Guido originally wanted to use a different exception for returning with a value, but he changed his mind.
Will the the delegating generator remain on the call-stack or not?
It certainly shows up in tracebacks, but I'm not actually sure whether it will be seen by sys._getframe() while a subiterator is running in my current implementation. I'll try an experiment to find out.
Even if it does, it's probably not something you should rely on, since a different implementation that optimizes more aggressively could behave differently.
In the case of thread-local storage for generator based threads, I don't think I would try to attach them to a generator frame, because a thread isn't just a single generator, it's a collection of generators.
Rather I'd use the scheduler to manage them. The scheduler knows when it's switching from one thread to another and can switch in the appropriate set of variables.