mnesia_schema.erl

transform_obj(Tab, RecName, Key, Fun, [Obj|Rest], NewArity, Type, Ws, Ds) ->
    NewObj = Fun(Obj),
    if
        size(NewObj) /= NewArity ->
            exit({"Bad arity", Obj, NewObj});
	NewObj == Obj ->
	    transform_obj(Tab, RecName, Key, Fun, Rest, NewArity, Type, Ws, Ds);
        RecName == element(1, NewObj), Key == element(2, NewObj) ->
            transform_obj(Tab, RecName, Key, Fun, Rest, NewArity, 
			  Type, [NewObj | Ws], Ds);
	NewObj == delete -> 
	    case Type of 
		bag -> %% Just don't write that object
		   transform_obj(Tab, RecName, Key, Fun, Rest, 
				 NewArity, Type, Ws, Ds); 
		_ ->
		    transform_obj(Tab, RecName, Key, Fun, Rest, NewArity, 
				  Type, Ws, [NewObj | Ds])
	    end;
        true ->
            exit({"Bad key or Record Name", Obj, NewObj})
    end;