On Sat, 19 Mar 2022 at 14:06, Greg Ewing <greg.ew...@canterbury.ac.nz> wrote: > > On 19/03/22 9:40 am, Rathmann wrote: > > The other challenge/question would be to see if there is a way to implement > > this basic approach with lower overhead. > > My original implementation of yield-from didn't have this problem, > because it didn't enter any of the intermediate frames -- it just > ran down a chain of C pointers to find the currently active one. > > At some point this was changed, I think so that all the frames > would show up in the traceback in the event of an exception. > This was evidently seen as more important than having efficient > resumption of nested generators. > > I'm not sure exactly how it works now, but I believe it involves > re-executing the YIELD_FROM bytecode in each generator down the > chain whenever a resumption occurs. This is nice and simple, but > not very efficient. > > Maybe another way could be found of preserving the traceback, > such as temporarily splicing the chain of frames into the call > stack and then resuming the last one. >
This is a fundamentally difficult problem with async/await too, so if there's any good solution, it would be worth carrying across. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
