# How to handle cmake COMPONENTS name change between 8.2 and 9.
**URL:** https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338
**Category:** Support
**Created:** [March 7, 2021, 4:54am UTC](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338 "2021-03-07T04:54:01Z")
**Posts on this page:** 12
**Page:** 1
### Author:  [@Luke\_Dalessandro](https://discourse.vtk.org/u/Luke_Dalessandro)
#### Post date: [March 7, 2021, 4:54am UTC](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338/1 "2021-03-07T04:54:01Z")
I’ve been using vtk8.2 successfully for a while now, with a basic
```auto
find_package(VTK REQUIRED COMPONENTS
vtkCommonCore
vtkCommonDataModel
vtkIOXML)
```
however, vtk9 changed those component names. How do I know which component names I should ask for without already knowing which version of VTK find\_package is going to find? Am I doing this wrong?
(edit: to be clear, I need to support both versions until everyone upgrades to 9)
---
### Author:  [@amaclean](https://discourse.vtk.org/u/amaclean)
#### Post date: [March 7, 2021, 9:02am UTC](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338/2 "2021-03-07T09:02:55Z")
Look at the CMakeLists.txt file in these [Cxx examples](https://kitware.github.io/vtk-examples/site/Cxx/), this may help.
---
### Author:  [@Luke\_Dalessandro](https://discourse.vtk.org/u/Luke_Dalessandro)
#### Post date: [March 7, 2021, 3:31pm UTC](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338/3 "2021-03-07T15:31:11Z")
Hi Andrew, thanks for the suggestion. The first couple of these just ask for the `vtk`-prefixed components which no longer exist in vtk9, as described by my post. Is there something else that I am supposed to be seeing?
---
### Author:  [@amaclean](https://discourse.vtk.org/u/amaclean)
#### Post date: [March 7, 2021, 7:17pm UTC](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338/4 "2021-03-07T19:17:38Z")
This approach works with VTK 9.0. For old versions of VTK ` include(${VTK_USE_FILE})`, just pulls in those modules, for VTK 9.0 all modules are pulled in: `MODULES ${VTK_LIBRARIES}`. Note that `QUIET` allows CMake to continue if a module doesn’t exist. The list of modules are the VTK 8 ones. Try an example. Alternatively test for each VTK version.
---
### Author:  [@Luke\_Dalessandro](https://discourse.vtk.org/u/Luke_Dalessandro)
#### Post date: [March 7, 2021, 7:52pm UTC](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338/5 "2021-03-07T19:52:05Z")
Hi Andrew, thanks for the information. So if I pass QUIET that silences the deprecation warnings that I get, but it’s still deprecated. Is there some modern replacement solution that isn’t deprecated?
```auto
CMake Deprecation Warning at /opt/homebrew/lib/cmake/vtk-9.0/vtk-config.cmake:64 (message):
The new name for the 'vtkRenderingOpenGL2' component is 'RenderingOpenGL2'
Call Stack (most recent call first):
CMakeLists.txt:5 (find_package)
```
(edit: grammar)
---
### Author:  [@amaclean](https://discourse.vtk.org/u/amaclean)
#### Post date: [March 7, 2021, 9:33pm UTC](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338/6 "2021-03-07T21:33:17Z")
Yes there is, if you build VTK yourself then, for VTK 9+, there is this Python script [FindNeededModules.py](https://gitlab.kitware.com/vtk/vtk/-/blob/master/Utilities/Maintenance/FindNeededModules.py). This will look at your code and determine what modules are needed. To do this, it needs **`modules.json`** found in your build directory. This is probably the best approach. It does mean that you have two sets of modules, one for VTK 9+ and one for the old version of VTK.
For example, for [CylinderExample](https://kitware.github.io/vtk-examples/site/Cxx/GeometricObjects/CylinderExample/), running the above Python script will give you:
```auto
find_package(VTK
COMPONENTS
CommonColor
CommonCore
FiltersSources
RenderingCore
# These modules are suggested since they implement an existing module.
# Uncomment those you need.
# InteractionStyle # implements VTK::RenderingCore
# RenderingFreeType # implements VTK::RenderingCore
# RenderingOpenGL2 # implements VTK::RenderingCore
# RenderingUI # implements VTK::RenderingCore
)
```
---
### Author:  [@Luke\_Dalessandro](https://discourse.vtk.org/u/Luke_Dalessandro)
#### Post date: [March 7, 2021, 9:50pm UTC](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338/7 "2021-03-07T21:50:07Z")
I’m sort of lost.
I have never build vtk. Our HPC users don’t build vtk. They get it from dpkg, homebrew, spack, etc. (depending on if they have root or not), or from a system-installed module. I have no control over what version they have installed (I only use its IOXML layer in order to provide vtu/pvd for paraview visualization of simulation results), nor do I plan on building it as a dependency.
If I already knew that I was going to find vtk9 (and thus might be able to track down that python script and add python as a dependency and run some magic cmake code to get it to generate the `COMPONENTS` in time for `find_package`) I wouldn’t have this problem because I could just request the proper names to start with.
I think I have a basic misunderstanding of the problem I’m trying to solve. I don’t know the vtk version until I’ve called `find_package`, but I need the version-dependent `COMPONENT` names in order to call `find_package`… classic catch-22.
I guess I’m just going to live with the `QUIET` flag until it finally breaks and then come back to figuring this out.
---
### Author:  [@amaclean](https://discourse.vtk.org/u/amaclean)
#### Post date: [March 7, 2021, 10:55pm UTC](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338/8 "2021-03-07T22:55:09Z")
How about this (this is untested). `CommonCore` will be always there so if `find_package` finds it you have VTK 9+, otherwise test for `vtkCommonCore`.
This gives you the VTK Version.
Then based on the version re-run `find_package`.
```auto
find_package(VTK COMPONENTS CommonCore QUIET)
if (NOT VTK_FOUND)
find_package(VTK COMPONENTS vtkCommonCore QUIET)
if (NOT VTK_FOUND)
message("Skipping ${PROJECT_NAME}: ${VTK_NOT_FOUND_MESSAGE}")
return ()
endif()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
# old system
find_package(VTK COMPONENTS
vtkCommonColor
vtkCommonCore
vtkCommonDataModel
vtkFiltersSources
vtkInteractionStyle
vtkRenderingContextOpenGL2
vtkRenderingCore
vtkRenderingFreeType
vtkRenderingGL2PSOpenGL2
vtkRenderingOpenGL2
)
else()
# new system
find_package(VTK COMPONENTS
CommonColor
CommonCore
CommonDataModel
FiltersSources
IOImage
RenderingCore
# These modules are suggested since they implement an existing module.
# Uncomment those you need.
InteractionStyle # implements VTK::RenderingCore
# RenderingFreeType # implements VTK::RenderingCore
RenderingOpenGL2 # implements VTK::RenderingCore
)
endif()
message(STATUS "VTK Libraries: ${VTK_LIBRARIES}")
```
I hope this helps. You may have to manually determine what other extra VTK 9 modules are needed.
---
### Author:  [@Luke\_Dalessandro](https://discourse.vtk.org/u/Luke_Dalessandro)
#### Post date: [March 7, 2021, 11:22pm UTC](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338/9 "2021-03-07T23:22:06Z")
Ah, this helps a lot. I didn’t realize I could effectively call `find_package` multiple times with different `COMPONENTS`. Thank you!
---
### Author:  [@amaclean](https://discourse.vtk.org/u/amaclean)
#### Post date: [March 7, 2021, 11:30pm UTC](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338/10 "2021-03-07T23:30:41Z")
Glad to help
---
### Author:  [@ben.boeckel](https://discourse.vtk.org/u/ben.boeckel)
#### Post date: [March 8, 2021, 1:49pm UTC](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338/11 "2021-03-08T13:49:02Z")
The deprecation warning is just saying that the old names aren’t going to be supported forever. If you explicitly declare that you need 8.2+ (or something), it suppresses those as well since you need to use the old names to support the version you’re stating. If you say `find_package(VTK 9.0)`, support for the old names is removed since you are saying you require 9.0 anyways (use of `VTK_USE_FILE` is also a hard error in this case).
I would recommend using the old names and declaring your minimum version (probably 8.0?). That will allow you to use the old names without warnings or any other complicated queries.
---
### Author:  [@Luke\_Dalessandro](https://discourse.vtk.org/u/Luke_Dalessandro)
#### Post date: [March 8, 2021, 4:57pm UTC](https://discourse.vtk.org/t/how-to-handle-cmake-components-name-change-between-8-2-and-9/5338/12 "2021-03-08T16:57:57Z")
Hi Ben,
Your suggestion makes complete sense, thank you.
Our initial support was for VTK6 but I removed a lot of that code once the slow-to-adopt-new-packages cluster moved up to 8. I stopped worrying about the version at that point. Then I independently realized that using the `COMPONENTS` style `find_package` meant I wasn’t looking for and linking the entire world. The change in component names threw me for a loop.
Luke