Dynamically storing properties depending on position

How you write the code depends on what class the code is associated with.  "this" will be identifying the class object, which based on your description will be a tile, so if you want to assign the direction of some other object (the character) then you want to target that character, not "this"

When you declare the function, you use the word "function", not "var"

When you declare the variables you should designate what class they are, and they should be declared outside the function if you intend that they be available outside of the class.

So the code might look something like this but only you can figure out how you actually want to program it and what you actually intended for each thing you showed....

public var xdir:int;

public var ydir:int;

private function giveTileDirections():void

{

          xdir = character.dirx;

          ydir = character.diry;

}