On 20Sep2010 15:41, James Yonan firstname.lastname@example.org wrote: [...] | * Develop a full-featured standard async result type and reactor | model to facilitate interoperability of different async libraries. | This would consist of a standard async result type and an abstract | base class for a reactor model. | | * Let PEP 3148 focus on the problem of thread and process pooling | and leverage on the above async result type. | | The semantics that a general async type should support include: | | 1. Semantics that allow you to define a callback channel for results | and and optionally a separate channel for exceptions as well. | | 2. Semantics that offer the flexibility of working with async | results at the callback level or at the generator level (having a | separate channel for exceptions makes it easy for the generator | decorator implementation (that facilitates "yield | function_returning_async_object()") to dispatch exceptions into the | caller). | | 3. Semantics that can easily be used to pass results and exceptions | back from thread or process pools. [...]
Just to address this particular aspect (return types and notification), I have my own futures-like module, where the equivalent of a Future is called a LateFunction.
There are only 3 basic types of return in my model:
there's a .report() method in the main (Executor equivalent) class that yields LateFunctions as they complete.
A LateFunction has two basic get-the result methods. Having made a LateFunction: LF = Later.defer(func)
You can either go: result = LF() This waits for func's ompletion and returns func's return value. If func raises an exception, this raises that exception.
Or you can go: result, exc_info = LF.wait() which returns: result, None if func completed without exception and None, exc_info if an exception was raised, where exc_info is a 3-tuple as from sys.exc_info().
At any rate, when looking for completion you can either get LateFunctions as they complete via .report(), or function results plain (that may raise exceptions) or function (results xor exceptions).
This makes implementing the separate streams (results vs exceptions) models trivial if it is desired while keeping the LateFunction interface simple (few interface methods).
Yes, I know there's no timeout stuff in there :-(