Thanks Jason,<div>I will add my examples when I get a chance. </div><div><br></div><div><div>Ivan Willig</div><br><br>
<br><br><div class="gmail_quote">On Tue, Oct 26, 2010 at 10:59 AM, Jason Roberts <span dir="ltr"><<a href="mailto:jason.roberts@duke.edu">jason.roberts@duke.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
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<p class="MsoNormal"><span style="font-size:10.0pt;color:#1F497D">Ivan, Frank,</span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#1F497D"> </span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#1F497D">A month ago I started a gotchas page with Even Rouault that
discusses this issue: <a href="http://trac.osgeo.org/gdal/wiki/PythonGotchas" target="_blank">http://trac.osgeo.org/gdal/wiki/PythonGotchas</a>.
If you have a moment, please consider adding your examples as other cases that
cause the lifetime problem. Also (Frank) if there is any general advice you
wish to add, it would be greatly appreciated.</span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#1F497D"> </span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#1F497D">Best,</span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#1F497D">Jason</span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;color:#1F497D"> </span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt">From:</span></b><span style="font-size:10.0pt"> <a href="mailto:gdal-dev-bounces@lists.osgeo.org" target="_blank">gdal-dev-bounces@lists.osgeo.org</a>
[mailto:<a href="mailto:gdal-dev-bounces@lists.osgeo.org" target="_blank">gdal-dev-bounces@lists.osgeo.org</a>] <b>On Behalf Of </b>Ivan Willig<br>
<b>Sent:</b> Tuesday, October 26, 2010 10:54 AM<br>
<b>To:</b> Frank Warmerdam<br>
<b>Cc:</b> <a href="mailto:gdal-dev@lists.osgeo.org" target="_blank">gdal-dev@lists.osgeo.org</a><br>
<b>Subject:</b> Re: [gdal-dev] Issue with python bindings.</span></p>
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<p class="MsoNormal"> </p>
<p class="MsoNormal">Thanks Frank. That seems to be the issue. Whats the rule
about this how long you should keep a reference. For example this causes the
same issue. </p>
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<p class="MsoNormal"> </p>
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<p class="MsoNormal">ds.GetLayer().GetFeature(0).GetGeometryRef().GetEnvelope()</p>
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<p class="MsoNormal"> </p>
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<p class="MsoNormal">Which I am going to guess is because I should keep a
reference to the geometry. Correct? </p>
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<p class="MsoNormal">Ivan Willig</p>
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<br>
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<p class="MsoNormal">On Tue, Oct 26, 2010 at 10:44 AM, Frank Warmerdam <<a href="mailto:warmerdam@pobox.com" target="_blank">warmerdam@pobox.com</a>> wrote:</p>
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<div>
<p class="MsoNormal">Ivan Willig wrote:</p>
<p class="MsoNormal">Hi list,<br>
I am having an issues with using the python swig based bindings. I am on Fedora
13 using the default gdal rpm, which is at version 1.6.2. My issue is when i
stack method calls. For example when I do the following: <br>
ogr.Open("/home/ivan/dev/bigapps/data/nyco.shp").GetLayer().GetFeature(0)<br>
<br>
<br>
I get a Segmentation fault. Here are the results of strace <a href="http://paste.pocoo.org/show/281682/" target="_blank">http://paste.pocoo.org/show/281682/</a>.
What am I doing wrong? Should I just hand compile a new version of gdal? Or is
this not an advised usage of the python bindings? A limitation in swig? Thanks
for your help.</p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Ivan,<br>
<br>
I believe the problem is object lifetimes. Keep a reference to the<br>
datasource around until you are done with the feature(s).<br>
<br>
ds = ogr.Open("/home/ivan/dev/bigapps/data/nyco.shp")<br>
feat = ds.GetLayer().GetFeature(0)<br>
...<br>
feat = None<br>
ds = None<br>
<br>
Best regards,<br>
<span style="color:#888888">-- <br>
---------------------------------------+--------------------------------------<br>
I set the clouds in motion - turn up | Frank Warmerdam, <a href="mailto:warmerdam@pobox.com" target="_blank">warmerdam@pobox.com</a><br>
light and sound - activate the windows | <a href="http://pobox.com/~warmerdam" target="_blank">http://pobox.com/~warmerdam</a><br>
and watch the world go round - Rush | Geospatial Programmer for
Rent</span></p>
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<p class="MsoNormal"> </p>
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