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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Forgive my non-C-ness (it’s been a long time since I wrote
a native module for Python), but aren’t you now buying into a major re-implementation
of all the native Python standard library into C#? <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Assuming for a moment that few sane people will want to
re-compile them from source, it seems much easier to just use the current
C++/CLI compiler from MS (not MC++), as recommended on the Mono site: <a
href="http://www.mono-project.com/CPlusPlus">http://www.mono-project.com/CPlusPlus</a>
(#CodeGeneration)<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Then conditionally switch out the CRT references with a CLR
version:<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>#ifdef CLR<o:p></o:p></span></p>
<p class=MsoNormal style='text-indent:.5in'><span style='font-size:11.0pt;
font-family:"Calibri","sans-serif";color:#1F497D'>Tasty, non-CRT happy-happy<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>#else<o:p></o:p></span></p>
<p class=MsoNormal style='text-indent:.5in'><span style='font-size:11.0pt;
font-family:"Calibri","sans-serif";color:#1F497D'>Evil, CRT hurty-hurty<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>#endif<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>.. Then maybe re-submit back to CPython-land.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
users-bounces@lists.ironpython.com [mailto:users-bounces@lists.ironpython.com] <b>On
Behalf Of </b>Curt Hagenlocher<br>
<b>Sent:</b> Wednesday, October 17, 2007 2:31 PM<br>
<b>To:</b> Discussion of IronPython<br>
<b>Subject:</b> Re: [IronPython] [python] Re: Announcement: Project to get
someCPython C extensions running under IronPython<o:p></o:p></span></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<div>
<p class=MsoNormal><span class=gmailquote>On 10/17/07, <b>Michael Foord</b>
<<a href="mailto:fuzzyman@voidspace.org.uk" target="_blank">fuzzyman@voidspace.org.uk
</a>> wrote:</span> <o:p></o:p></p>
<p class=MsoNormal>I would be sad if we chose any approach that couldn't work
on Mono. :-(<o:p></o:p></p>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>I agree. Assuming this rules out MC++, I think the
next best approach is (as Paolo suggests) to try to shift as much of the work
to C# as possible.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>Here's an architecture to think about. Consider the
following example for PySequence_Length:<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>In C:<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>typedef int
(__stdcall *PFN_iO)(PyObject *);</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>PFN_iO
PFN_PySequence_Length;</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>void
Set_PySequence_Length(PFN_iO callback)<br>
{<br>
PFN_PySequence_Length = callback;<br>
}<br>
int PySequence_Length(PyObject * object)<br>
{<br>
return PFN_PySequence_Length(object); <br>
}</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>In C#:<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>public delegate int
PFN_iO(IntPtr object);</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>[DllImport("extension.DLL")]<br>
public static extern void Set_PySequence_Length(PFN_iO callback);</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>public
static int PySequence_Length(IntPtr obj_in)</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>{</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>
object o = ObjectConverter(obj_in);</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>
// Do something with o</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>
return result;</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>}</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>public static void
SetApiFunctionsAtStartup()</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>{</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>
Set_PySequence_Length(PySequence_Length);</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-family:"Courier New"'>}</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>Ignoring exception-handling for now, the idea is to keep
most of the implementation in C# and to have the C# code register callback
functions as actual implementations for the parts of the Python API that we're
going to duplicate. <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>This is idea is dependent on a kind of "global
registry" of objects with representations on both sides of the
border. Such a registry will almost certainly be required in order to
translate between the two -- if for no other reason than to handle
reference-counting and/or garbage collection. Any PyObject being passed
across the boundary would then actually be some kind of index into the
registry. <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>A "PyTuple_New" would call through the delegate
into C# where (say) a List<object> would be created and added to the
registry, with its unique identifer being passed back to the C caller as a
"PyObject *". <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>INCREF and DECREF on the C side would affect a reference
count in the registry. Once the DECREF takes the reference count down to zero,
the object is removed. At that point, it may very well still be a valid
CLR object in use by other parts of the program -- just not by the C extension.
<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>Objects actually defined in the C extension would be
required to use either PyObject_New or Py_NewReference as part of their
initialization in order for the proper fixups to happen.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>What do you think?<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>--<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal>Curt Hagenlocher<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><a href="mailto:curt@hagenlocher.org">curt@hagenlocher.org</a><o:p></o:p></p>
</div>
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