clj1.clj

clj1.clj

;; factory functions

(defn order-query-of-field1
  [v]
  {:type :field1, :value v})

(defn order-query-of-field2
  [v1 v2]
  {:type :field2, :v1 v1, :v2 v2})

(defn order-query-of-field3
  [v]
  {:type :field3, :value f})

;; DB functions
(defn filter-by-field1 [db query] (throw (RuntimeException. "Not implemented")))
(defn filter-by-field2 [db query] (throw (RuntimeException. "Not implemented")))
(defn filter-by-field3 [db query] (throw (RuntimeException. "Not implemented")))

;; varianta 1

;; ala switch implementace
(defn filter-by
  [db query]
  (case (:type query)
    :field1 (filter-by-field1 db query)
    :field2 (filter-by-field2 db query)
    :field3 (filter-by-field3 db query)))

(let [repository {} ;; připojení do DB
      query (order-query-of-field1 "asdf")
      orders (filter-by repository query)]))
      

;; varianta 2

;; ala switch implementace s parametrizací (DI)
(defn filter-by
  [filter-by-field1 filter-by-field2 filter-by-field3 query]
  (case (:type query)
    :field1 (filter-by-field1 query)
    :field2 (filter-by-field2 query)
    :field3 (filter-by-field3 query)))

(let [repository {} ;; připojení do DB
      query (order-query-of-field1 "asdf")
      orders (filter-by (partial filter-by-field1 repository)
                        (partial filter-by-field2 repository)
                        (partial filter-by-field3 repository)
                        query)]))