Fix merge for an Instance (workaround for clj-commons/potemkin#70) (#46)

Author: camsaul

.dir-locals.el

@@ -9,5 +9,6 @@
                   (eval . (put 'p/def-map-type 'clojure-doc-string-elt 2))
                   (eval . (put-clojure-indent 'p/defprotocol+ '(1 (:defn))))
                   (eval . (put-clojure-indent 'p/def-map-type '(2 nil nil (:defn))))
+                  (eval . (put-clojure-indent 'p/deftype+ '(2 nil nil (:defn))))
                   (eval . (put-clojure-indent 'with-meta '(:form)))
                   (eval . (put-clojure-indent 'with-bindings* '(:form))))))

src/toucan2/instance.clj

@@ -67,6 +67,22 @@
       (Instance. model orig m new-meta)))
 
   clojure.lang.IPersistentCollection
+  (cons [this o]
+    (cond
+      (map? o)
+      (reduce #(apply assoc %1 %2) this o)
+
+      (clojure.core/instance? java.util.Map o)
+      (reduce
+       #(apply assoc %1 %2)
+       this
+       (into {} o))
+
+      :else
+      (if-let [[k v] (seq o)]
+        (assoc this k v)
+        this)))
+
   (equiv [_this another]
     (cond
       (clojure.core/instance? toucan2.protocols.IModel another)

src/toucan2/magic_map.clj

@@ -30,7 +30,7 @@
   "The default magic map transform function. Converts things to `kebab-case`, preserving namespaces."
   [k]
   (when k
-    (if (and (clojure.core/instance? clojure.lang.Named k) (namespace k))
+    (if (and (instance? clojure.lang.Named k) (namespace k))
       (keyword (->kebab-case (namespace k)) (->kebab-case (name k)))
       (keyword (->kebab-case (name k))))))
 

test/toucan2/instance_test.clj

@@ -411,3 +411,10 @@
                empty-instance))
         (is (instance/instance? empty-instance))
         (is (instance/instance-of? ::venues empty-instance))))))
+
+(deftest ^:parallel merge-test
+  (let [m (instance/instance ::birds {:name "Parroty"})]
+    (are [m2 expected] (= expected
+                          (merge m m2))
+      {:type :parakeet} {:name "Parroty", :type :parakeet}
+      nil               {:name "Parroty"})))