Make SISL optional

[arneboe]

The mainfest defines sisl as optional but base-types does not compile without sisl. This PR fixes that issue.

This reduces the number of dependencies that we need to install when using base-types outside of rock. In our use case we are dependent on base types but not on Spline/Trajectory, thus we do not need the SISL dependency.

[doudou]

I would rather that this is controlled by an explicit option (i.e. WITH_SISL), to avoid having people getting an unexpectedly crippled base/types.

[chhtz]

Adding an option would be fine for me.

However, I don't understand how this should interact with <depend package="external/sisl" optional="1" /> from package.xml. If the dependency is not found, would it still be mandatory to manually set the option?

Perhaps we could always install Spline.hpp and Trajectory.hpp, but have it generate an #error, if SISL was not found?

[arneboe]

Perhaps we could always install Spline.hpp and Trajectory.hpp, but have it generate an #error, if SISL was not found?

This shifts the error to the compile phase instead of the configuration phase where it should occur.

In general I am fine with an option but it conflicts with having optional=1 in the manifest.

[doudou]

In general I am fine with an option but it conflicts with having optional=1 in the manifest.

Not necessarily. Autoproj will have to set the flag if sisl is not excluded, which would be done with

unless Autoproj.manifest.excluded?('external/sisl')

end

Within the package definition block in rock.core's 02stable.autobuild

Note that the package_enabled? call is actually deprecated since Autoproj v2. To facilitate the transition between v1 and v2, I disabled the deprecation warnings by default and then forgot I did :(

[doudou]

Closing this now that #134 has been merged.