Eh, nevermind, I refactored things a bit, and I'm happier now. Sorry
for the noise.
;;;;;;;;;;;;;;;;; base ;;;;;;;;;;;;;;;;;;;;;;;;
(defrecord Entity [id asset location data])
(defrecord Farmer [entity])
(defn get-entity-by-key
([] (fn [this] (:entity this)))
([key] (fn [this] (key this))))
(defprotocol Inspectable
(inspect [_])
(get-entity [_]))
(defn base-inspect [this]
(let [e (get-entity this)]
(println "entity" (:id this) "@" (:location e) (:data e))))
(def base-behavior {
:get-entity (fn [this] this)
:inspect base-inspect
})
(extend Entity
Inspectable
base-behavior)
;;;;;;;;;;;;;;;;; survival ;;;;;;;;;;;;;;;;;;;;;;;;
(defprotocol Survive
(find-food [_]))
(defn base-survive [this]
(let [e (get-entity this)]
(println "entity" (:id e) "looking for food")))
(def survival-behavior {
:find-food base-survive
})
;;;;;;;;;;;;;;;;; farmer ;;;;;;;;;;;;;;;;;;;;;;;;
(extend Farmer
Inspectable
(merge base-behavior {:get-entity (get-entity-by-key)})
Survive survival-behavior)
On Dec 6, 3:08 pm, tmountain <[email protected]> wrote:
> 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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