Re: [newbie] Question on embedding/extending with boost::python

From: David Abrahams (dave_at_[hidden])
Date: 2003-05-27 06:30:27

Chris, please post your Boost.Python questions to the C++-sig:
http://www.python.org/sigs/c++-sig/

"Chris Heald" <yg-boost-users_at_[hidden]> writes:

> Hi all --
>
> I'm working on an app that is going to be a C++ code engine which will be
> heavily extended through a series of Python scripts (objects, really). My
> desired requirements are as follows:
>
> The environment is a C++ state machine, and each Python object should
> persistantly maintain its own state. I assume I can instanciate a Python
> object and maintain it in C++, then call it when necessary.
>
> a) Embed the Python interpreter
> b) Be able to pass values from the C++ state machine into the Python object
> for internal use
> c) Be able to call arbitrary Python functions from C++. I am currently doing
> this with an event registration handler, where scripts will handle events
> they want to handle, along with the function that should be called when the
> event is fired.
> d) Be able to update the C++ state machine with an interface exposed from
> C++
>
> I can do a and b easily enough - the examples make that clear. Where I'm
> having trouble is with c and d - how do I give a Python app hooks into an
> existing C++ state machine? I know I can write an extension easily enough,
> but by my understanding, that will simply give the Python object access to a
> series of functions, and not the objects contained in the state machine that
> the interpreter is running under. I could use "pull" operations, wherein the
> C++ app polls the objects for changed state in a loop and updates its sate
> accordingly, but that seems that it wouldn't perform nearly so well as if
> the Python scripts were able to update the C++ state machine themselves, so
> I'm avoiding that route.
>
> I had a co-worker suggest that I use Python as my primary execution
> environment instead of C++. While this would admittedly make some things
> easier, how much performance would I sacrifice with this route? I'm building
> a 3D application, and it doesn't seem that Python would be well-suited to
> such an application in terms of performance. There is potential for
> literally tens of thousands of instances of these objects to exist in this
> state machine, and I certainly don't want to hinder performance by moving
> the primary execution into an interpreted environment rather than a compiled
> environment.
>
> Any words of wisdom? Or am I utterly failing to communicate clearly, as I
> think I am? ;)
>
> Thanks,
>
> Chris

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com