Rather than performing complicated upgrade procedures from the old (broken) logic in three activity modules, we are adding new capabilities to those three modules to make them all consistent, and using them in a callback from the Ratings API. This is the same as the Comments API.
The downside is that two sets of capabilities need to be enabled for ratings to work. Hopefully this can be mitigated somewhat when build some sort of shortcuts on the module settings forms to set capabilities. In the meantime, the effect is reduced somewhat by having all the rating capabilities enabled by default for student and teacher roles. This means control is in the hands of whatever the modules have set, giving very close backward compatibility.
This is not the perfect solution, but neither were the other two.
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WARNING: DEV IS CURRENTLY VERY UNSTABLE.
This is a mega-checkin of the new Roles system. A lot of changes have
been made in core and modules.
Currently there are a lot of rough edges and known problems. We are
working hard on these .. .the reason for getting this into HEAD at this
stage is enable us to move faster (our branch was diverging from HEAD
too much).
Please keep an eye on http://docs.moodle.org/en/Roles for current status
and information for developers on how to use the new Roles system.
Aparup Banerjee