We now compute the average CBM score, accuracy, CBM bonus and enhanced
accuracy, both for the entire quiz, and for just the questions answered.
Note that these calculations must work correctly in the presence of
descriptions, ungraded questions, and manually graded questions. For
example, imagine a essay added at the end of the quiz "Summarise what
you learned attempting this exercise." This might have max mark zero or
non-zero. The CBM statistics just ignores questions like that.
At the top of the quiz reivew page, there is a table that summarises
infomration about the quiz attempt as a whole. For some question
behaviours, we would like to be able to add additional information to
that summary.
This commit introduces a generic method for the behaviour to provide
summary information about an entire question usage.
It was always a bit of a hack to use static methods on the
qbehaviour_whatever classes to return metadata about the behaviour. It
is better design to have real qbehaviour_whatever_type classes to report
that metadata, particularly now that we are planning to add more such.
For example, inheritance works better with real classes. See, for
example, the improvements in
question_engine::get_behaviour_unused_display_options().
This change has been implemented in a backwards-compatbile way. Old
behaviours will continue to work. There will just be some developer debug
output to prompt people to upgrade their code properly.
Tim Hunt