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<p class=MsoNormal><span lang=EN-US>Hi,<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>I’m evaluating IronPython for use as a
scripting language in a game server. Designers would use it for game-logic.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Because designers typically are not
engineers, one cannot expect them to follow common good practices. So I need to
restrict what their script code can do in a few ways:<o:p></o:p></span></p>
<p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span
lang=EN-US><span style='mso-list:Ignore'>a.<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span lang=EN-US>They should not be able to use
any libraries other than what we expose to them explicitly. That includes
Python libraries (other than local) and .NET-Framework libraries.<o:p></o:p></span></p>
<p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span
lang=EN-US><span style='mso-list:Ignore'>b.<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span lang=EN-US>For framework classes it’s
necessary to expose only certain members of these classes that are meant to be
used from Python.<o:p></o:p></span></p>
<p class=MsoListParagraph style='text-indent:-18.0pt;mso-list:l0 level1 lfo1'><![if !supportLists]><span
lang=EN-US><span style='mso-list:Ignore'>c.<span style='font:7.0pt "Times New Roman"'>
</span></span></span><![endif]><span lang=EN-US>It should be possible to
time-limit execution time of a script. Designers might build scripts that under
certain circumstances enter an infinite loop or something similar. In such a
case, script execution should be aborted.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Now with a) it’s easy enough to take
away access to Python libraries. Neither is there a problem with .NET framework
stuff because you need to add a reference explicitly – with two
exceptions, mscorlib.dll and system.dll are referenced automatically. I wrote a
patch to get around this (PythonEngine and ReflectedPackage). With this patch
you have two boolean properties in EngineOptions, AutoReferenceMscorlib and
AutoReferenceSystem which by default are set to true to keep behavior as it is,
but can be set to false, too, with the expected effect.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>For b) it turns out there is no easy way of
having a framework classes expose only certain methods/properties by for
example passing only an interface to Python. That just doesn’t work
because Python will allow access to any public member of the concrete instance.
One way around that would be to write adapter for each framework class (like: for
class Player create class PythonPlayer which holds an instance of Player as
private member and exposes only those members publicly that should be visible
from Python), but that would be tedious. So I created another patch (Attributes
and ReflectedType) which adds a new attribute [DoNotExpose] to IronPython. Framework
code writers can decorate properties, methods, fields, nested types etc. with
this attribute. Members decorated such won’t be visible to Python code.
Again, by default behavior is not changed as no code has this attribute.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>With c) I am stuck. I’m not at all
sure where I could add such functionality with minimum impact to the existing
codebase.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Any ideas on that?<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Besides, any feedback to the patches would
be most welcome, too.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Happy Easter holidays,<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Max Hajek<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US>Vienna<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US><o:p> </o:p></span></p>
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