[Python-Dev] PEP 334 - Simple Coroutines via SuspendIteration (original) (raw)

Clark C. Evans cce at clarkevans.com
Wed Sep 8 05:29:25 CEST 2004

Josiah Carlson kindly pointed out (off list), that my use of SuspendIteration violates the standard idiom of exceptions terminating the current function. This got past me, beacuse I think a generator not as a function, but rather as a shortcut to creating iterators. The offending code is,

| def NonBlockingResource(): | yield "one" | while True: | rand = randint(1,10) | if 2 == rand: | break | raise SuspendIteration() | yield "two"

There are two solutions: (a) introduce a new keyword 'suspend'; or, (b) don't do that.

It is not essential to the proposal that the generator syntax produce iterators that can SuspendIteration, it is only essential that the implementation of generators pass-through this exception. Most non-blocking resources will be low-level components from an async database or socket library; they can make iterators the old way.

Cheers,

Clark

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