You could probably make a general function and put it in a system NPC, or a class. Most servers will have a WNPC or class dedicated specifically for general functions, like math functions, that can be used between a multitude of NPCs. Add this in a global WNPC or a class that's joined to the player:
PHP Code:
//#CLIENTSIDE
public function moveplayer(dx,dy) {
// do movement stuff here
}
Then if it's a WNPC, you can simply call WeaponName.moveplayer(0,-100); or if it's a player class, player.moveplayer(0,-100);