Also don't forget that you could set key and retrieve it in this way you don't need many public variable..
As for example:
You create 5 trigger trap, you set a key like this "Type of entity" = 1 (1 trap, 2 ai, 3 player, 4..) , when 2 entity collide you can get the key, also you could set other value to them as for example the "effect" you need to reproduce.