Integrating Fast-DDS into a project without installing external dependencies system wide.

[Renegade85]

Hello,

we are using Fast-DDS library in our project. We would like to update our build system to CMake. A simplified structure of our project looks like this:

project
+-- CMakeLists.txt
+-- 3rdparty
    +--Fast-DDS
    +--foonathan_memory_vendor

The projects CMakeLists.txt file looks following way:

1 cmake_minimum_required (VERSION 3.16)
2
3 message(STATUS "default install: ${CMAKE_INSTALL_PREFIX}")
4
5 set (THIRDPARTY ON CACHE STRING "" FORCE)
6 set (BUILD_SHARED_LIBS OFF CACHE STRING "" FORCE)
7
8
9 add_subdirectory(3rdparty/foonathan_memory_vendor)
10 add_subdirectory(3rdparty/Fast-DDS)
11

I've tried to generate a build configuration, but this fails due to the fact, that Fast-DDS uses find_package(foonathan_memory_vendor), however, that package is not installed in the system and I don't want to install it system wide. Unfortunately I can't figure out, how to make this running, as I'm a cmake newbie. Any help would be really appreciated.

Second question related to this is, why is the foonathan_memory_vendor used instead of the original foonathan_memory?
Why is the foonathan_memory "included" as an external dependency and is not part of the thirdparty directory as other libs?

Thanks a lot for your help

[JLBuenoLopez]

Hi @Renegade85

foonathan_memory_vendor is an auxiliary package to check if foonathan_memory is installed and if not, download and install it. If you look into the CMakeLists.txt in eProsima repository, what is required there is find_package(foonathan_memory). Maybe you have been misled by Fast DDS installation guide. In those instructions, foonathan_memory_vendor is directly used instead of asking the user to install the package by their own. But you can remove the vendor dependency if you have already installed foonathan_memory in your system.

[Renegade85]

Hi @JLBuenoLopez-eProsima

I see. The find_package( ) requires the module/package to be installed, is that correct? I'm using the add_subdirectory way to include things, so this won't work. Am I correct? Or can I use the add_subdirectory(foonathan_memory) (not the vendor one) and it will work without the need to install the package?

I'm sorry, I'm new to cmake and I still miss all the relationships between modules etc.

[JLBuenoLopez]

Fast DDS current configuration does not allow to include foonathan_memory with the add_subdirectory approach. This should be fixed including foonathan_memory in the thirdparty directory as you pointed in your opening question. You might want to look at #3818 which has a workaround to use add_subdirectory to include foonathan_memory.

[Renegade85]

Do I understand the issue #3818 that you plan to add the foonathan as a submodule under thirdparty or it was just a suggestion?

[JLBuenoLopez]

We will try to do it but I cannot promise a specific time frame.

[Renegade85]

Thanks a lot for your help