cmake PROJECT_IS_TOP_LEVEL (#252)

[jbaldwin]

This reverts commit f6b9b7f.

This commit needs to include package manager creation for conan and vcpkg before it can be merged since it broke building for at lesat conan.

[jbaldwin]

@stripe2933 unfortunately a portion of the PR for PROJECT_IS_TOP_LEVEL broke the conan builds so we reverted that portion of it. I've created a revert revert of it to make sure it isn't lost since it seems like its a good idea still.

What probably needs to happen is a a github actions job to build the conan package needs to be added and pass with this change.

The reported bug user noticed that cmake 3.25 or greater didn't have a problem, but I don't think its a good idea to upgrade the project to that new of a cmake version yet.

[stripe2933]

It's okay. I couldn't test the code validity for CMake < 3.25 since my environment is CMake 3.28. I hope if there is any solution for this PR's intention.

[jbaldwin]

See #259 CI addition for Conan so once that is merged I believe your original change should be testable and we can see if it'll work with cmake < 3.25

[uilianries]

It's okay. I couldn't test the code validity for CMake < 3.25 since my environment is CMake 3.28. I hope if there is any solution for this PR's intention.

Hello! I see some options to have multiple CMake versions in your environment without breaking your current one.

• You could use python pip with install cmake, but with a python environment (pyenv)
• Or, you could use some C++ package manager like Conan to install and run using a temporary path.

@jbaldwin We could add a test with multiple CMake versions in the CI to check it, if you think it's okay.

[jbaldwin]

I think that is definitely a reasonable solution if we move forward again with this project is top level.

But let me ask another question, what about just switching the defaults to OFF? I had originally had them on since it's super nice if you are just exploring the repo but I think far more users at this point are probably linking to it so perhaps it's better to default to OFF?