[DGD] Referencing an array of variable depth

[Robert Forshaw]

Imagine a situation where you have an array of arrays, and the first element 
of each array may contain another array of arrays. At some point you want to 
change a value of all the arrays.

To briefly go over the problem I have, I've got an global array called 
action_queue, which stores 'actions' which are arrays storing particular 
data. One of the elements of this 'action' might store another action_queue, 
or in other words, another array of actions. These are sub-actions.

Now let's say I'm making a function called extend_current_action, which 
modifies another element (let's call it interval) of every action stemming 
off from the first action. So in one situation you might have the 
action_queue array, the first element of that being the current action, and 
the first element of the current action being a sub-array (another action 
queue), the first element of that being the current sub-action. Let's say 
there's one more sub-action below that sub-action... so the first element of 
the sub-action contains another sub-array containing another action queue, 
the first element of that being the current sub-sub action!

And now what I want to do, is modify the elements of all those actions, the 
current action, the current sub-action, and the current sub-sub-action. In 
this situation I've described, the depth of the arrays is 3 (or 6 if you 
include the queues), but the depth is variable. if it were fixed, 
accomplishing what I want would be much easier.

I can't see any clean way to reference the sub-arrays, even if the 
extend_current_action is informed of the depth. There are two possible but 
undesirable ways I can see to do it:

1) Build a string containing the expression I want to perform on the arrays. 
I.e.

string * expressions;
string expression;
int count;

expressions = allocate(depth);

expressions = action_queue[0];
for(count = 0; count < depth; count++)
{
    expressions[count] = expression + "[INTERVAL] = time;";
    expression[count] += "[SUB_ACTION_QUEUE][0];
}

------------------

There's a glaring flaw in this solution though, namely that there is no 
built in way to turn a string into an expression (as far as I'm aware). The 
only way to do it is to write it into a seperate file and run that, but that 
won't work when trying to reference global variables of a particular object.

2) Do a long and contrived switch statement checking for all the possible 
values of 'depth' and then executing the appropriate expression. i.e.

switch(depth)
{
    case 0:
        action_queue[0][INTERVAL] = time;
    break;
    case 1:
        action_queue[0][INTERVAL] = time;
        action_queue[0][SUB_ACTION_QUEUE][0][INTERVAL] = time;
    break;
/* aaaand so on... */

Which is unsightly to say the least. There must be a more efficient solution 
I've overlooked, surely?

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