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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">You can just use a normal try/catch. IronPython has a mapping between .NET exceptions and Python exceptions. We actually have documentation on this over
here <a href="http://ironpython.codeplex.com/wikipage?title=Exception%20Model">http://ironpython.codeplex.com/wikipage?title=Exception%20Model</a>. But apparently it’s out of date for StopIteration. For that we now define our own StopIterationException in
IronPython.Runtime.Exceptions which you can catch.<o:p></o:p></span></p>
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color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D">For 2.7 we’ve added support for light exceptions – so if you’re downloading the source from CodePlex you’ll see some methods are decorated with a [LightThrowing]
attribute. Those methods will return a value which is actual a wrapped exception. For those you can use the LightExceptions class to see if the return value is a light exception and the code will look more like what you have below.<o:p></o:p></span></p>
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<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>Tristan Zajonc<br>
<b>Sent:</b> Tuesday, June 08, 2010 10:26 AM<br>
<b>To:</b> Discussion of IronPython<br>
<b>Subject:</b> [IronPython] Checking for Python exception in C#<o:p></o:p></span></p>
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<p class="MsoNormal">Hi,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I'm trying to get my head around the IronPython API by implementing a simple work-around for what I believe is a bug in the next() builtin,which I reported here: <a href="http://ironpython.codeplex.com/workitem/27383" target="_blank">http://ironpython.codeplex.com/workitem/27383</a>.
This is my first look inside IronPython so this question, I assume, is pretty basic. How can I handle Python exceptions returned by TryInvokeUnaryOperator? I'm currently trying to do this to implement the default value argument in the next builtin.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> public static object next(CodeContext/*!*/ context, object o) {<o:p></o:p></p>
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<p class="MsoNormal"> object value;<o:p></o:p></p>
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<p class="MsoNormal"> if (PythonTypeOps.TryInvokeUnaryOperator(context, o, "next", out value)) {<o:p></o:p></p>
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<p class="MsoNormal"> return value;<o:p></o:p></p>
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<p class="MsoNormal"> }<o:p></o:p></p>
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<p class="MsoNormal"> throw PythonOps.TypeError("{0} object is not an iterator.", PythonTypeOps.GetName(o));<o:p></o:p></p>
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<p class="MsoNormal"> }<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> public static object next(CodeContext/*!*/ context, object o, object defaultVal) {<o:p></o:p></p>
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<p class="MsoNormal"> object value = next(context, o);<o:p></o:p></p>
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<p class="MsoNormal"> // This doesn't work.<o:p></o:p></p>
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<p class="MsoNormal"> if (value is StopIterationException) {<o:p></o:p></p>
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<p class="MsoNormal"> return defaultVal;<o:p></o:p></p>
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<p class="MsoNormal"> }<o:p></o:p></p>
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<p class="MsoNormal"> return value;<o:p></o:p></p>
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<p class="MsoNormal"> }<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thanks,<o:p></o:p></p>
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<p class="MsoNormal">Tristan<o:p></o:p></p>
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