I know this problem well. I have my own package that does it, along with several documents full of crufty code. I can tell you my implementation:
Permuting answer choices:
- Use a
pgfmath
list to store the answer choices
- Do a Knuth shuffle on that list to permute them
- Walk over the list printing out each choice
You might find the \pgfmathsetseed
command useful because you want randomized choices but the same randomized choices each time you compile! You might also find http://random.org/ good for getting sufficiently random seeds.
For generating multiple versions and answer keys I use docstrip
. My main file is a docstrip file like exam.dtx
and I use guards like
%<A>\pgfmathsetseed{1001} % seed for A version
%<B>\pgfmathsetseed{1010} % seed for B version
%<*key>
% commands that alter whether the key is shown
%</key>
to \generate
files like exam-A.tex
, exam-A-key.tex
, etc. Then you have one document per file without manually repeating code.
I don't use the exam
class but I think this could work in that.