[ITK-dev] ITK and old expat library

[Bradley Lowekamp]

Hello,

As the symbols in the ITK library are not managled. So if you try to use the a system expat in conjunction with the ITK expat you could have conflicting symbols and undefined behavior. Simply installing the header in a different location will not solve this problem.

Configuring ITK to use a system expat will fully solve you problem.

You can find how other third party libraries did it here:

https://github.com/InsightSoftwareConsortium/ITK/blob/master/Modules/ThirdParty/JPEG/CMakeLists.txt
https://github.com/InsightSoftwareConsortium/ITK/blob/master/Modules/ThirdParty/TIFF/CMakeLists.txt

Would you like to try to create a patch to address this issue?

Thanks,
Brad

On Jun 2, 2014, at 8:22 AM, Rashad M <mohammedrashadkm at gmail.com> wrote:

> 
> 
> 
> On Mon, Jun 2, 2014 at 2:07 PM, Bradley Lowekamp <blowekamp at mail.nih.gov> wrote:
> Hello,
> 
> It would be quite reasonable to support using a system expact.
> 
> Could you please describe you problem a little clearer? Are you having problem compiling ITK? or an Application which uses ITK? or Issues compiling independent programs after ITK is installed?
> 
> My problem not with compiling/installing ITK but when compiling libkml, a dependency of OTB which uses ITK. This uses an expat library and instead of using  a system expat i wind up using expat from ITK as expat.h is installed in <prefix>/include/ITK4.6. I can confirm using system expat doesnt have any problem with libkml when used with OTB. 
> 
> If you would like to have a look at bug report, see here[1]. I had a temporary solution to build libkml before adding itk headers but a best would be to have a fix in ITK' expat library.
> 
> The issue is coming using an installed version of ITK. 
> So if you are planning to upgrade expat library to its latest version or use system expat then the problem is solved. 
> 
> [1] http://bugs.orfeo-toolbox.org/view.php?id=879
>  
> 
> 
> 
> Thanks,
> Brad
> 
> On Jun 1, 2014, at 3:29 AM, Rashad M <mohammedrashadkm at gmail.com> wrote:
> 
>> Hi,
>> 
>> Is there an option to install expat includes in a different location? For now its installed in <prefix>/include. This seems to be a problem when using a latest expat version and by default ITK's expat is included. 
>> 
>> Or if it is possible to use a system expat to make sure that both ITK and other libraries uses same expat (latest version).
>> 
>> best would be to change location <prefix>/include/expat. So that cmake can be used to remove item from list of include directories.
>> 
>> eg:
>> list(REMOVE_ITEM expat-includes itk-includes)
>> 
>> -- 
>> Regards,
>>    Rashad
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> 
> 
> 
> 
> -- 
> Regards,
>    Rashad

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