Simple shelf puzzle?

[The chaser]

You could use a "for" in this case.

void OnStart()
{
for (int i = 1, i =30, i++) ///Supposing that there are 30 stuff
{
AddEntityCollideCallback("Stuff"+i, "Area", "Call", true, 1);
}

void Call (string &in asParent, string &in asChild, int alState)
{
AddLocalVarInt("Shelf_variable", 1);
check();
}

void check()
{
if (GetLocalVarInt("Shelf_variable")==30)
{
/////Let the player interact and do something with the shelf
}
}