wrapper - How to encapsulate in clojure? -

i have clojure code looks this:

(defn rect [x y w h]   {:x x, :y y, :w w, :h h})  (def left :x) (def top :y) (def width :w) (def height :h)  (defn right [r]   (+ (left r) (width r)))  (defn bottom [r]   (+ (top r) (height r))) 

now following code seems bit uncommon:

(def left :x) 

however don't know other way encapsulation.

suppose, later want represent rect different way. relying on (:x rect) not idea, because :x works on hashmap's , records, leaking implementation details in api, @ least in oo languages considered bad practice.

now, if decide implement rect in java instead, gets worse, because have write wrappers like:

(defn left [rect] (.getleft rect)) 

to make sure interface doesn't change.

how clojure around problem?

you can use protocols.

first clojure record:

(defprotocol rectangular   (left [this])   (right [this]))  (defrecord rect [x y w h]   rectangular   (left [this] x)   (right [this] (+ x w)))  (def my-rect (rect. 1 2 3 4)) (right my-rect) ;=> 4 

now java object:

(import java.awt.rectangle)  (extend-type rectangle   rectangular   (left [this] (int (.getx this)))   (right [this] (int (+ (.getx this) (.getwidth this)))))  (def my-other-rect (rectangle. 1 2 3 4)) (right my-other-rect) ;=> 4