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PORetrieving the Return Value of a Stackless Python Tasklet Bound Function?
 

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    <p>Stackless Experts,</p> <p>I have managed to create tasklets under Stackless Python (both from the Stackless and the C side).</p> <p>It seems to me that in order to create a tasklet in Stackless, you bind an arbitrary Python callable (function) to the tasklet (as well as the required parameters), so the bound callable would be run as a tasklet. However, an arbitrary callable might actually have a return value that's important to the caller. But I have yet to see a way to retrieve the return value of the bound callable running as a tasklet.</p> <p>On the pure Stackless Python side, I do see a usage idiom called Micromanaging, which wraps the original function with a managing function, which in turn <em>could</em> capture the return value of the original function and save it somewhere for use in some other context.</p> <p>Unfortunately, my special use case involves creating a tasklet from the C (C++) side, binding to a (potentially blocking) Python callable which has an important return value to be used later. It seems that writing such a Micromanaging function on the C side is not very feasible, since I haven't found a way to turn a C function into a PyObject callable dynamically (not involving module table initialization, etc.), and using static stateless C function (I would assume the prototype has to be PyObject* (PyObject*, PyObject*)) is generally a bad idea under C++ world anyways.</p> <p>The Stackless C API also seems not containing a proper function to retrieve the return value of a tasklet. Is it the only option that I have to write above mentioned Micromanaging function (<em>could</em> be stateful) in Python, and provide a way to retrieve the return value saved somewhere (in a stateful fashion, i.e. not using global variables)? Or there could be other options I could possibly explore?</p> <p>Thank you very much,</p> <p>Lin</p> <p>P.S. I understand that on the C and operating system level programming, the return value of a thread function is only meaningful for exit code, and thread functions would have a strict function prototype, i.e. C functions have to abide by some strict rules to become runnable as/by a thread. And now we are talking about Python :)</p>
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