Guido van Rossum wrote:
BTW, I'd really like it if you (and others interested in PEP 380) read Dave Beazley's excellent coroutines tutorial (http://dabeaz.com/coroutines/), and commented on how yield-from can make his example code easier to write or faster.
The place where yield-from enters the picture would be in Part 8 ("The Problem with the Stack"), where it would eliminate the need for the scheduler to do trampolining of calls and returns. The idea of yield being like a system call is an interesting perspective. Imagine what it would be like if ordinary programs had to make system calls every time they wanted to call or return from a function! That's the situation we have now when using generators as coroutines, and it's the problem that yield-from addresses. -- Greg