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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Thank you, it would be awesome to have this (and the other proposed hints, too).<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">Andras<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"><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> David Gobbi [mailto:david.gobbi@gmail.com]
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<b>Sent:</b> Friday, August 4, 2017 1:06 PM<br>
<b>To:</b> Andras Lasso <lasso@queensu.ca><br>
<b>Cc:</b> VTK Developers <vtk-developers@vtk.org><br>
<b>Subject:</b> Re: Safer item access in Python wrapped VTK arrays<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi Andras,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Yes, this would be possible. It could be hard-coded into the wrappers, or even better, in the header file a generic hint could be added to the index parameter so that the index would be checked against the size of the array:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> float GetValue(vtkIdType idx VTK_RANGECHECK(0,GetNumberOfValues()));<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 have a list of wrapper hints at <a href="https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.vtk.org%2FWiki%2FVTK%2FWrapping_hints&data=02%7C01%7Classo%40queensu.ca%7C6b328e9098d3473fb04408d4db5b2a7f%7Cd61ecb3b38b142d582c4efb2838b925c%7C1%7C0%7C636374631984021366&sdata=zFV%2By8tHBbAW%2FZbScngLl1qPfsgemLkAxVfPsKRPNZI%3D&reserved=0">http://www.vtk.org/Wiki/VTK/Wrapping_hints</a>,
and I can add this "RANGECHECK" hint to the "Proposed hints" section.<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 hoping to find time to implement more of these wrapper hints over the next few weeks.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> - David<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">On Fri, Aug 4, 2017 at 9:53 AM, Andras Lasso <<a href="mailto:lasso@queensu.ca" target="_blank">lasso@queensu.ca</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Hi David,</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Users who mostly use VTK via Python wrapping are sometimes surprised how easily they can crash the
application by accessing out-of-bounds elements in arrays. For example, this crashes an application:</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:8.5pt;font-family:Courier;color:black">>>>
</span><span style="font-size:8.5pt;font-family:Courier;color:#000096">a=vtk.vtkStringArray()</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:8.5pt;font-family:Courier;color:black">>>>
</span><span style="font-size:8.5pt;font-family:Courier;color:#000096">print(a.GetValue(0))</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:8.5pt;font-family:Courier;color:#000096"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">I first thought that it should be handled by documentation and training, but it would be nicer if the
wrappers could handle this.</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Would it be feasible to add bounds check to VTK array accessors in Python wrappers, so that in case
of an out of bounds access, a Python exception would be raised instead of crashing the application?</span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Andras</span><span style="color:#888888"><o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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