[pymvpa] New PyNIfTI release (was: pynifti ref-count bugs?)

[Michael Hanke]

Hi,

On Wed, Oct 08, 2008 at 12:05:39PM +0200, Michael Hanke wrote:
> On Wed, Oct 08, 2008 at 11:26:43AM +0200, Gael Varoquaux wrote:
> > On Wed, Oct 08, 2008 at 11:14:14AM +0200, Michael Hanke wrote:
> > > The file should be correct, but the way you access the array causes
> > > trouble. getDataArray() simply returns a pointer to the data allocated
> > > by the nifti library. As you do not store the nifti image itself, that
> > > data is destroyed immediately, hence segfault when accessing it.
> > 
> > Ha, OK. It did seem that the data was being derefenced, but it wasn't
> > clear to me that this was the expected behavior.
> > 
> > > Just replace getDataArray() (or simply .data) with asarray(), which has
> > > a parameter 'copy' that is True by default.
> > 
> > Why is the copy necessary? It seems that this should simply be a refcount
> > increment, rather than the copy. Travis Oliphant has a nice blog post on
> > a cool way to do this:
> > http://blog.enthought.com/?p=62
> Good pointer! I guess the reason why it is not implemented like this is
> that the blog post is dated "September 9th, 2008" ;-)
I have released a new version of PyNIfTI. Together with some minor
updates it now also handles the refcount issue properly. If I got it
right, there should be no need for unnecessary copying anymore and it
should be safe to simply use .data instead of asarray().

Thanks again for the pointer,

Michael


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