A little problem triggering things...

[themanofum]

(Synopsis below)

I've been working on a RTS (real time strategy) video game for quite a while now, and have decided over time to implement a system of "triggers". Those with previous knowledge of such games would know that triggers are system used in games to tell things to perform actions when a certain event occurs in the game world. However, I'm rather clueless on where to begin with the implementation of this trigger system.

The way the trigger would work would be simple. One or a series of variables are tripped by other things in the game world (time passing, objects moving to a certain place, etc.), and the trigger then tells several events to occur as a result of this. (money being given or units being destroyed).

The problem I'm encountering in the early stages of implementation of this system is the dynamic nature of the variables that can activate any given trigger. One type of trigger may say "when a tank goes to location A and the player has 5000 dollars, destroy a tank in location B" while another may say "when 500 frames have passed, give the player 2000 dollars and blow up his defenses". So no one constructor would work to make a trigger which could be used with all the necessary properties.

Synopsis :
What I need is something that can create a trigger (or condition-like) object that can have changing amounts of multiple variables of different classes within a single constructor. Any ideas on how to do something like this, or the counsel of anybody who has stumbled on this problem before would be greatly appreciated.

[Belisarius]

Well, you could keep a central registry of all the game-objects in a singleton, then the triggers would be able to look through all the elements it needs to in order to see if the condition has been satisfied.

[themanofum]

The problem isn't keeping track of the objects, it's that the type of constructor needed varies so greatly from trigger type to trigger type

for example, one type of trigger may need an int, an int, and a double to operate whereas another may need a String, an int, a double and a char to operate, and there are too many of these guys to just mass-produce constructors to all of them.

the type of thing I'm looking for is a way to have a constructor be able to take any combination of data types or objects and use them appropriately based on the type of trigger it is

Edit : problem solved! Strings can be used to hold all the necessary information! thanks for trying belisarius

[Deliverance]

It seems to me that your trigger system objects only share one thing in common:

Trigger interface.

In this case, I'd recommend a factory class that can construct a type of trigger based on your parameter criteria. Going further on this, it seems every trigger needs to execute() as well.

You'll find that String manipulation is very expensive in processing depending on your criteria (remember that they are immutable).

[themanofum]

well, the trigger would only be parsed once, and there would only be a few hundred at the absolute maximum, so really, the high costs of using strings are bearable