Hi, I'm playing around with protocols and records and trying to
implement some ad-hoc type composition. I have a solution that works,
but I want to make it more readable. Specifically, if you look at the
code below, I'd like to come up with a macro or some other solution to
eliminate all the calls to (get-this this). Ideally, I could just say
something like (:id (self)) or something along those lines. The
reasoning for having a get-this method should become evident as your
read the code. It's basically an abstraction for calling derived
behaviors.
(defrecord Entity [id asset location data])
(defrecord Farmer [entity])
(defprotocol Inspectable
(inspect [_])
(get-this [_]))
(defprotocol Survive
(find-food [_]))
(defn base-inspect [this]
(println "entity" (:id this) "@" (:location (get-this this)) (:data
(get-this this))))
(def base-behavior {
:get-this (fn [this] this)
;:inspect (fn [this] (println "entity" (:id this) "@" (:location
(get-this this)) (:data (get-this this))))
:inspect base-inspect
})
(extend Entity
Inspectable
base-behavior)
(def survival-behavior {
:find-food (fn [this] (println "entity" (:id (get-this this))
"looking for food"))
})
(extend Farmer
Inspectable
(merge base-behavior {:get-this (fn [this] (:entity this))})
Survive survival-behavior)
(def thing (Entity. 1 :foo [0, 0] {}))
(inspect thing)
(def farmer (Farmer. thing))
(find-food farmer)
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