RE: Python and C++ code calling ROOT

From: Marc de Kamps <dekamps_at_comp.leeds.ac.uk>
Date: Fri, 18 Jul 2008 18:24:50 +0100

Dear Rootteam,

If this is what is happening, is it possible to "mark" libGX11.so, so that it knows that it is dependent on libCore.so? I would much prefer to use the shared libraries.

Sorry about reposting. I noted that the text below war grabeled in the earlier posting.

Marc

-----Original Message-----
From: owner-roottalk_at_lxbuild091.cern.ch
[mailto:owner-roottalk_at_lxbuild091.cern.ch] On Behalf Of Paul Russo Sent: 15 July 2008 20:39
To: Marc de Kamps
Cc: roottalk_at_lxbuild091.cern.ch
Subject: Re: [ROOT] Python and C++ code calling ROOT

Marc,

This is happening because libGX11.so is dependent on symbols in libCore.so but is not marked that way, so dlopen does not know it should load libCore.so when it loads libGX11.so. The ROOT application itself uses a plugin architecture with external metadata to determine the interdependencies
between the various shareable libraries that together make up the ROOT library set (see the *.rootmap files in $ROOTSYS/lib).

The simplest way around this problem for you is to build a static version of the root library from the source code using "make static". This will make a libROOT.a file which you can then link with your code, avoiding all problems with *.so files.

• Paul Russo

Marc de Kamps wrote:
> Hi,
>
>
>
> As I mentioned last week I have C++ code which calls ROOT. Using SWIG I
> create a Python module. The idea is that from Python I can call my C++
> routines, which call ROOT.
>
>
>
> This turns out to be problematic. I have to link against a library which
> is linked against the core ROOT libraries (root-config -libs). Python
> then crashes on importing my SWIG generated libraries.
>

>> >> import Dynamic

>
> dlopen error: /usr/not-backed-up/root/lib/root/libGX11.so: undefined
> symbol: _ZNK7TObject7DoErrorEiPKcS1_Pc
>
> Load Error: Failed to load Dynamic link library
> /usr/not-backed-up/root/lib/root/libGX11.so
>
> Error in <TCint::AutoLoad>: failure loading library libGX11.so for class
> TGX11
>
> Error in <TPluginHandler::SetupCallEnv>: class TGX11 not found in plugin
> GX11
>
>
>
> Followed by a core dump. Apparently autoload is called but fails. Is
> there anything I can do about this?
>
>
>
> Repeating the same exercise with root-config -glibs has the same result.
>
>
>
> If I don't link my libraries against ROOT I get:
>
> Python 2.5 (r25:51908, Apr 10 2007, 10:29:13)
>
> [GCC 4.1.2 20070403 (Red Hat 4.1.2-8)] on linux2
>
> Type "help", "copyright", "credits" or "license" for more information.
>

>> >> import Dynamic

>
> Traceback (most recent call last):
>
> File "<stdin>", line 1, in <module>
>
> File "Dynamic.py", line 7, in <module>
>
> import _Dynamic
>
> ImportError: /tmp/code/build/libs/DynamicLib/libmiinddynamic.so:
> undefined symbol: _ZN10TCanvasImp11ShowMembersER16TMemberInspectorPc
>

>> >> 

>
> (which seems reasonable)
>
>
>
> I use root 5.19/02 on FEDORA Linux
>
>
>
> I have also tried to load libCore.so directly into Python using
> LoadLibrary. This does not work because it complains about a missing
> symbol in libCint.so. If I try to load libCInt it complains about a
> missing symbol in libCore.so ..
>
>
>
>
>
>
>
> -
>
> Dr. Marc de Kamps
>
> Biosystems Group
>
> School of Computing
>
> University of Leeds
>
> LS29JT, Leeds, UK
>
>
>
> dekamps_at_comp.leeds.ac.uk <mailto:dekamps_at_comp.leeds.ac.uk>
>
> http:/www.comp.leeds.ac.uk/dekamps
>
>
>
Received on Fri Jul 18 2008 - 19:26:01 CEST