[Ironpython-users] Gradually executing a python script

Kevin Hazzard wkhazzard at gmail.com
Mon Jul 23 20:13:23 CEST 2012


What you're describing is a state machine. There are many ways to build
such a thing and honestly, I've never thought of single-stepping through
code as a way to do that. It's actually quite an intriguing idea, if not
inefficient. But efficiency isn't always measured with elegance (and vice
versa). Keith's settrace idea is good, too. You should check that out.

What it really comes down to is this: do you want the controller to also
define the code or merely to drive it? For the example you posted, do you
want the while loops implemented in Python to execute your dostuff() and
dootherstuff() methods? Or do you want the controller that authorizes a
"step" to do that? In that context, you could write the controller in
Python, too, but the design of your code would look very different than
what you proposed.

Kevin

On Mon, Jul 23, 2012 at 1:48 PM, Jesper Taxbøl <jesper at taxboel.dk> wrote:

> The reason I want to do it gradually is that I cant be sure that the
> script ever terminates or has syntax errors. Would that not be a problem in
> a turn based setup?
>
>
> 2012/7/23 Keith Rome <rome at wintellect.com>
>
>>  You may want to look into leveraging the sys.settrace() feature of
>> Python for controlling line-by-line execution. This API allows you to
>> install a profiling function that gets invoked for every frame of script
>> code that is executed. In your profiling function, you could compute the
>> amount of memory being used by variables within the ScriptScope, and halt
>> execution if you need to. Just be careful about what you do in your
>> profiling function, as it will be called extremely often by the runtime.*
>> ***
>>
>> ** **
>>
>> http://docs.python.org/library/sys.html#sys.settrace****
>>
>> ** **
>>
>> ** **
>>
>> The reason you are seeing variant results is probably due to how you have
>> implemented multithreading. The IronPython runtime is mostly thread-safe
>> (as long as you don’t use libraries that make use of mutable objects, and
>> as long as you import all libraries used at least once prior to forking
>> threads). But your code must also be thread-safe as well. From your
>> descriptions of your game engine, it sounds like your game engine is not
>> designed to be thread-safe so I would strongly recommend avoiding
>> multithreading as a means of providing resource sharing. It is very
>> difficult to write 100% thread-safe code, and nothing will stop people from
>> writing unsafe scripts in your game.****
>>
>> ** **
>>
>> Instead, I would suggest implementing your game engine as a turn-based
>> system. For each turn, the script for each character is executed
>> completely. This will allow you to cycle through all characters one turn at
>> a time, equally, and will also eliminate the problem of having variant
>> outcomes since the program will become deterministic.****
>>
>> ** **
>>
>> ** **
>>
>> ** **
>>
>> *Keith Rome*
>>
>> *Senior Consultant and Architect*
>>
>> MCPD-EAD, MCSD, MCDBA, MCTS-WPF, MCTS-TFS, MCTS-WSS****
>>
>> Wintellect | 770.617.4016 | krome at wintellect.com <rome at wintellect.com>***
>> *
>>
>> www.wintellect.com****
>>
>> ** **
>>
>> *From:* ironpython-users-bounces+rome=wintellect.com at python.org [mailto:
>> ironpython-users-bounces+rome=wintellect.com at python.org] *On Behalf Of *Jesper
>> Taxbøl
>> *Sent:* Monday, July 23, 2012 11:05 AM
>> *To:* Kevin Hazzard
>> *Cc:* ironpython-users at python.org
>> *Subject:* Re: [Ironpython-users] Gradually executing a python script****
>>
>> ** **
>>
>> Would that allow me to step gradually through a loop?****
>>
>> ** **
>>
>> like:****
>>
>> ** **
>>
>> x = 0****
>>
>> while x < 10:****
>>
>>    dostuff()****
>>
>>    x=x+1****
>>
>> while x > 0:****
>>
>>    dootherstuff()****
>>
>>    x=x-1****
>>
>> ** **
>>
>> ** **
>>
>> ** **
>>
>> 2012/7/23 Kevin Hazzard <wkhazzard at gmail.com>****
>>
>> Why don't you use a scripting host and inject commands into a
>> ScriptEngine reusing a ScriptScope as you need to execute them?****
>>
>>  ****
>>
>> Kevin****
>>
>> On Mon, Jul 23, 2012 at 5:31 AM, Jesper Taxbøl <jesper at taxboel.dk> wrote:
>> ****
>>
>>  Hi,****
>>
>> ** **
>>
>> I am not that familiar with Ironpython yet, but I have a question that I
>> hope you can help me answer.****
>>
>> ** **
>>
>> I am working on a programming-game where I will allow users to do some
>> simple python scripting against a simple API that I will control a game
>> character. Instructions like move and shoot etc, alongside some simple
>> sense functions that return info on the game world. ****
>>
>> ** **
>>
>> My current prototype creates an ironpython engine for each game character
>> and executes the script in a thread by itself, which sort of works. But I
>> have the problem that the outcome of executing the game gives different
>> results every time. Therefore I would like to ask the question:****
>>
>> ** **
>>
>> Is it possible to execute a script inside the Ironpython engine gradually?
>> ****
>>
>> ** **
>>
>> I imagine that I could update a list of engines with a tick(int cycles)
>> and get a fair sharing of resources between engines and ensure the same
>> result every time.****
>>
>> ** **
>>
>> Kind regards ****
>>
>> ** **
>>
>> Tax****
>>
>> ** **
>>
>> ** **
>>
>> P.S:****
>>
>> As this is a programming game I would also like to be able to limit the
>> available memory each script is using. Is there a way to limit this, so a
>> script like this would be killed.****
>>
>> ** **
>>
>> x = 0****
>>
>> v = {}****
>>
>> while True:****
>>
>>    v[x]=x****
>>
>>    x= x + 1****
>>
>> ** **
>>
>> ** **
>>
>> ** **
>>
>> _______________________________________________
>> Ironpython-users mailing list
>> Ironpython-users at python.org
>> http://mail.python.org/mailman/listinfo/ironpython-users****
>>
>>
>>
>>
>> --
>> *W. Kevin Hazzard*****
>>
>> Consultant, Author, Teacher, Microsoft MVP****
>>
>> (804) 928-3444****
>>
>> book <http://manning.com/hazzard> | mvp<https://mvp.support.microsoft.com/profile/Kevin.Hazzard>|
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>> ****
>>
>> ** **
>>
>> ** **
>>
>
>


-- 
*W. Kevin Hazzard*
Consultant, Author, Teacher, Microsoft MVP
(804) 928-3444
book <http://manning.com/hazzard> |
mvp<https://mvp.support.microsoft.com/profile/Kevin.Hazzard>|
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