[WWdevel] problem groups (in gateway tests)

[P. G. L. <gl...@um...>]

Hi all,

This is a question about adding problems to a set from a group of 
problems, which is done for gateway tests.  This is (only) implemented for 
versioned sets (that is, gateway tests).  The idea is that one can define 
a problem set (gateway test) for which each problem on the set is drawn 
from a group of possible problems.  (For example, on a derivative gateway 
test we might want one "derivatives of trig functions" problem, one 
"derivatives of exponentials", etc.)

This is done in the following manner.
  - a set, say, settopic1.def, is created that lists all of the problems in
    the group.  then
  - in the set definition for the set including a problem from the group
    declares the problem source to be "group:topic1"
  - this source file name is caught by the subroutine
    Instructor::assignProblemToUserSetVersion when a new version of the set
    is being created for the user, and the problem that is actually added
    to the user's set is randomly selected from the list of problems in the
    topic1 set.

I'm now thinking about how to include more than one problem from a problem 
group.

I think the logical way to do this is to refine the way problems are
selected from the group to include an indication of the number of problems
to be selected from the group.  That is, instead of having the set declare
a problem "group:topic1", have the declaration be "group:topic1:N", where
N is the number of problems to include.  Then when a new version of the
set is created and assignProblemToUserSetVersion is called, it would
actually add N problems to the user's set version.

An argument against this might be that it's aesthetically displeasing: the 
set is being created with Instructor:assignSetVersionToUser, which 
(currently) makes one call to assignProblemToUserSetVersion for every 
problem to be added to the set. What I've suggested above would push some 
of the "set construction" down into the problem assignment (because 
assignProblemToUserSetVersion could now be doing multiple assignments per 
"problem"), which seems logically incorrect.

The other option would be to allow multiple problems to be assigned from
the group, and to have some check built into assignProblemToUserSetVersion
that it's not assigning the same problem that's already been assigned.
But that would be rather more difficult to implement.

Any comments?

Thanks,
Gavin

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