robotology-superbuild source repositories directories will change in the next weeks

[traversaro]

Target Users

If you are using the robotology-superbuild only for installing software, for example by using the robotology-superbuild releases, this change will not impact you. Furthermore, this change will only impact releases of the superbuild that will be done in 2021.

If instead you are using the robotology-superbuild in rolling update workflow and you modify the source code of the robotology-superbuild packages, please ready in the following.

Old Behavior

If you are a user of the robotology-superbuild, you know that once you run the superbuild, as part of the build process all the git repositories for the superbuild packages will be cloned in two directories:

• robotology-superbuild/external In this directory, packages not developed in IIT or part of the robotology organization are contained
• robotology-superbuild/robotology In this directory, packages that are developed in IIT or part of the robotology organization are contained.

New Behavior

As discussed in robotology/robotology-superbuild#333, this will change in PR robotology/robotology-superbuild#556, that will instead ensure that all repos will be cloned in robotology-superbuild/src, regardless of their type.

Rationale

The rationale of this change is discussed in robotology/robotology-superbuild#333 , but it is reported in the following:

• Consistency: all the source repos will go in the same directory, and with a directory whose meaning is clear from its name.
• Familiarity for people used to ROS/ROS2/colcon: in ROS/ROS2 workspaces, all the repos are contained in the src subdirectory of the workspace
• We can use more easily the vcs tool (see https://github.com/dirk-thomas/vcstool) to manipulate the repos if they are in devel model, for example to export the value of all the repos in the superbuild. vcs is the tool used in ROS2, so it would be something familiar used to ROS2 workspaces. In theory vcs could be used also with the current directory structure, but the saved file would have the strange format of having the external or robotology directory prefixed to the CMake package name:

repositories:
  external/osqp:
    type: git
    url: https://github.com/oxfordcontrol/osqp
    version: master
  robotology/YARP:
    type: git
    url: https://github.com/robotology/yarp
    version: master

this would complexify its use as a reference for superbuild tags, while using a single src directory would result in a much more natural:

repositories:
  osqp:
    type: git
    url: https://github.com/oxfordcontrol/osqp
    version: master
  YARP:
    type: git
    url: https://github.com/robotology/yarp
    version: master

this YAML file can also be used to specify a set of custom version for the robotology-superbuild itself, using the ROBOTOLOGY_PROJECT_TAGS_CUSTOM_FILE option, as described in https://github.com/robotology/robotology-superbuild/blob/master/doc/change-project-tags.md .

Guidelines for affected users

If you are using the robotology-superbuild in rolling update workflow then pay attention that after you will update (i.e. git pull) the robotology-superbuild once https://github.com/robotology/robotology-superbuild#rolling-update is merged, your superbuild will use the src directory to store the repositories, instead of the external and robotology. To avoid confusion in which source files you will need to edit, it is suggested to either:

• do a clean clone and build of the superbuild
• or manually delete the external, robotology, build/external and build/robotology directories.

[traversaro]

The PR robotology/robotology-superbuild#556 has been merged, so from now on if you using the master branch of the robotology-superbuild the changes described in this discussion will be effective! If you instead you are using the released version of the robotology-superbuild, you will need to wait for the next release to experience this change.

[S-Dafarra]

cc @robotology/iit-dynamic-interaction-control