# Cannot wrapping module for python
**URL:** https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281
**Category:** Support
**Tags:** python
**Created:** [February 19, 2025, 11:34am UTC](https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281 "2025-02-19T11:34:36Z")
**Posts on this page:** 11
**Page:** 1
### Author:  [@Mat\_F](https://discourse.vtk.org/u/Mat_F)
#### Post date: [February 19, 2025, 11:34am UTC](https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281/1 "2025-02-19T11:34:36Z")
Hi all,
as I early mentioned on title, I’m trouble with the wrapping of custom classes to python. I had search for long time but i didnt found nothing to solve my case.
Below all steps to reproduce the error:
`git clone --depth 1 --branch v9.4.1 https://gitlab.kitware.com/vtk/vtk.git`
`cd vtk/Examples/Modules/Wrapping`
`python -m venv venv`
`source venv/bin/activate`
`pip install vtk`
`mkdir build && cd build`
```auto
cmake .. \
-DVTK_DIR=../venv/lib/python3.12/site-packages/vtkmodules/cmake \
-DCMAKE_BUILD_TYPE=Release \
-DVTK_WRAP_PYTHON=ON
```
`cmake --build .`
then I’ve copied “wrapping” folder from build/lib/python3/dist-packages/wrapping to venv/lib/python3.12/site-packages/
and copied “libvtkWrappable.so” from build/lib/ to venv/lib
after that
```auto
python
Python 3.12.7 (main, Feb 12 2025, 12:16:38) [GCC 13.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import wrapping.vtkWrappable
Errore di segmentazione (core dump creato)
```
I can’t say what goes wrong and I dont have found a solid guide to build correctly this wrapper.
The main goal is to subclass the vtkLegendScaleActor (in c++) in order to import on a python script beacuse I need to modify the logic on BuildRepresentation method, but for now I’m focusing to get a example build.
Can you help me to solve this? Thanks in advance
---
### Author:  [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)
#### Post date: [March 3, 2025, 11:09pm UTC](https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281/3 "2025-03-03T23:09:39Z")
> [@Mat\_F](#):
>
> then I’ve copied “wrapping” folder from build/lib/python3/dist-packages/wrapping to venv/lib/python3.12/site-packages/
Your VTK build is probably subtly incompatible with the wheel VTK. You might have better luck grabbing the relevant wheel SDK bundle (named `vtk-wheel-sdk-*` on [this page](https://vtk.org/download/)) and building projects against it.
---
### Author:  [@Mat\_F](https://discourse.vtk.org/u/Mat_F)
#### Post date: [March 20, 2025, 11:04am UTC](https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281/4 "2025-03-20T11:04:29Z")
Hi Ben, thanks for your reply.
Finally I have build the wrapper and works when imported on a custom venv. Now I’m facing another problem that concerns vtkCommonCore compatibiliy. My lib links to my system’s vtk lib, and I think need to build wrapper linking to venv vtk libs.
The error:
```python
from customodules.renderingAnnotation import LegendScaleActor
ImportError: Initialization failed for renderingAnnotation, not compatible with vtkmodules.vtkCommonCore
```
This appens when the vtk lib goes installed trough pip, but when I copy the entire vtk lib generated on my system (using the same version 9.4.1) this problem goes away.
In any case i need to use pip’s vtk lib.
Any suggestions?
---
### Author:  [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)
#### Post date: [March 20, 2025, 12:02pm UTC](https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281/5 "2025-03-20T12:02:15Z")
> [@Mat\_F](#):
>
> My lib links to my system’s vtk lib, and I think need to build wrapper linking to venv vtk libs.
Yes, you do. There are SDK bundles to be compatible with the wheels on the page I linked to [here](https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281/3).
---
### Author:  [@Mat\_F](https://discourse.vtk.org/u/Mat_F)
#### Post date: [March 20, 2025, 1:41pm UTC](https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281/6 "2025-03-20T13:41:23Z")
I’m trying to build it with your advice, but the lib points to system’s lib
```bash
ldd librenderingAnnotation.so
linux-vdso.so.1 (0x00007fff0d5c1000)
libvtkRenderingAnnotation-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkRenderingAnnotation-9.4.so.1 (0x000070fe2a751000)
libvtkRenderingFreeType-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkRenderingFreeType-9.4.so.1 (0x000070fe2a6ab000)
libvtkRenderingCore-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkRenderingCore-9.4.so.1 (0x000070fe2a400000)
libvtkCommonCore-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkCommonCore-9.4.so.1 (0x000070fe28a00000)
libvtksys-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtksys-9.4.so.1 (0x000070fe2a3a8000)
libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x000070fe28600000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x000070fe2a34e000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x000070fe28200000)
libvtkFiltersSources-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkFiltersSources-9.4.so.1 (0x000070fe2890c000)
libvtkFiltersGeneral-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkFiltersGeneral-9.4.so.1 (0x000070fe27c00000)
libvtkFiltersCore-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkFiltersCore-9.4.so.1 (0x000070fe27000000)
libvtkCommonExecutionModel-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkCommonExecutionModel-9.4.so.1 (0x000070fe284ed000)
libvtkCommonDataModel-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkCommonDataModel-9.4.so.1 (0x000070fe26800000)
libvtkCommonTransforms-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkCommonTransforms-9.4.so.1 (0x000070fe288c7000)
libvtkCommonMath-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkCommonMath-9.4.so.1 (0x000070fe2889d000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x000070fe27b17000)
libvtkfreetype-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkfreetype-9.4.so.1 (0x000070fe28435000)
libvtkCommonColor-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkCommonColor-9.4.so.1 (0x000070fe2a32d000)
libvtkCommonComputationalGeometry-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkCommonComputationalGeometry-9.4.so.1 (0x000070fe281ca000)
libvtkFiltersGeometry-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkFiltersGeometry-9.4.so.1 (0x000070fe26e81000)
libvtkCommonSystem-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkCommonSystem-9.4.so.1 (0x000070fe28415000)
libvtkCommonMisc-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkCommonMisc-9.4.so.1 (0x000070fe26200000)
libvtktoken-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtktoken-9.4.so.1 (0x000070fe28881000)
libvtkdoubleconversion-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkdoubleconversion-9.4.so.1 (0x000070fe27b05000)
libvtkloguru-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkloguru-9.4.so.1 (0x000070fe27af1000)
/lib64/ld-linux-x86-64.so.2 (0x000070fe2a897000)
libvtkFiltersVerdict-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkFiltersVerdict-9.4.so.1 (0x000070fe26e42000)
libvtkfmt-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkfmt-9.4.so.1 (0x000070fe27ac9000)
libvtkFiltersReduction-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkFiltersReduction-9.4.so.1 (0x000070fe26621000)
libvtkpugixml-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkpugixml-9.4.so.1 (0x000070fe261c3000)
libvtkkissfft-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkkissfft-9.4.so.1 (0x000070fe281c3000)
libvtkzlib-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkzlib-9.4.so.1 (0x000070fe26e24000)
libvtkverdict-9.4.so.1 => /usr/local/vtk-9.4.1/lib/libvtkverdict-9.4.so.1 (0x000070fe2618f000)
```
Can i ask you how to build correctly, step by step? Probably I’m missing somethiing but I don’t know what.
Thanks in advance
---
### Author:  [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)
#### Post date: [March 20, 2025, 1:46pm UTC](https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281/7 "2025-03-20T13:46:35Z")
@jcfr or @banesullivan Do you have experience using these SDKs?
---
### Author:  [@dgobbi](https://discourse.vtk.org/u/dgobbi)
#### Post date: [March 20, 2025, 5:38pm UTC](https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281/8 "2025-03-20T17:38:21Z")
I think this can be fixed by setting `INSTALL_RPATH` to something relative to `$ORIGIN` when you build your project, e.g. `$ORIGIN/../vtkmodules`. I’m foggy on the details because I haven’t worked with rpath-related settings recently.
---
### Author:  [@Mat\_F](https://discourse.vtk.org/u/Mat_F)
#### Post date: [March 21, 2025, 10:36am UTC](https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281/9 "2025-03-21T10:36:28Z")
Hi all,
I want to share some updates.
After serveral attemps I managed to build the lib with SDK download from [here](https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281/3) as suggested by Ben.
The SDK appears incomplete because can’t resolve symbols like “vtkObject::GetObjectDescription()”
```python
Python 3.12.7 (main, Feb 12 2025, 12:16:38) [GCC 13.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from mymodules import renderingAnnotation
Traceback (most recent call last):
File "", line 1, in
ImportError: /home/matteo/test/vtk_modules/Custom/venv/lib/python3.12/site-packages/mymodules/librenderingAnnotation.so: undefined symbol: _ZNK9vtkObject20GetObjectDescriptionB5cxx11Ev
```
What I’m missing now?
The SDK is [vtk-wheel-sdk-9.4.1-cp312-cp312-manylinux\_2\_17\_x86\_64.manylinux2014\_x86\_64.tar.xz](https://vtk.org/files/release/9.4/vtk-wheel-sdk-9.4.1-cp312-cp312-manylinux_2_17_x86_64.manylinux2014_x86_64.tar.xz)
In the other way, with full vtk built, this problem goes away, but cannot “communicate” with vtkCommonCore of pip’s version.
---
### Author:  [@dgobbi](https://discourse.vtk.org/u/dgobbi)
#### Post date: [March 21, 2025, 1:29pm UTC](https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281/10 "2025-03-21T13:29:21Z")
The missing symbol seems to be a mangling issue. The symbol provided by the SDK’s `libvtkCommonCore.so` is:
```
_ZNK9vtkObject20GetObjectDescriptionEv
```
But the symbol your build wants is
```
_ZNK9vtkObject20GetObjectDescriptionB5cxx11Ev
```
So the build is adding `B5cxx11` to the symbol. I’m not familiar with “Bnxxxx” mangling, but you can try adding the following to your CMakeLists.txt, which will match with the C++ std version used by the SDK:
```
set(CMAKE_CXX_STANDARD 11)
```
---
### Author:  [@dgobbi](https://discourse.vtk.org/u/dgobbi)
#### Post date: [March 21, 2025, 2:13pm UTC](https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281/11 "2025-03-21T14:13:39Z")
Follow-up: `B5cxx11` is `abi:cxx11`, which is described here:
[https://gcc.gnu.org/onlinedocs/libstdc++/manual/using\_dual\_abi.html](https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html)
According to that, `abi:cxx11` can be removed from symbols by adding this (e.g. to CMakeLists.txt):
```
add_definitions(-D_GLIBCXX_USE_CXX11_ABI=0)
```
The symbol for the `GetObjectDescription()` method is afflicted because it returns a string, and the ABI for strings changed between c++98 and c++11.
---
### Author:  [@Mat\_F](https://discourse.vtk.org/u/Mat_F)
#### Post date: [March 24, 2025, 9:28am UTC](https://discourse.vtk.org/t/cannot-wrapping-module-for-python/15281/12 "2025-03-24T09:28:27Z")
Hi all!
Friday on late I’ve resolved and I promised to myself to reply here today.
But I see only today that David has answer with the same solution that I’ve discovered too.
So thanks for the support and for answering. Probably that isn’t a best practice but for now is the only way that permits me to obtain an external library based on vtk wheel.
In any case if you got a better way to do that i’ll appreciate to know it.
For now thanks to all