I should add that I am at the moment using this workaround:

function p1_do_this{
me=player1;
do_this():
}

function p2_do_this{
me=player2;
do_this;
}

function do_this{
blah blah;}

action character1{
player1=me;
on_a = p1_do_this;
}

action character2{
player2=me;
on_b = p2_do_this;
}

Really I just wondered if there was a simpler way of doing this, without the intermediary steps...