Add backward aliases

src/zen/store.clj

@@ -47,7 +47,7 @@
                        (fnil conj #{})
                        (mk-symbol zen-ns ns-key)))))
 
-    (when (nil? res)
+    (when (and (nil? res) (not (contains? (:declares @ctx) resolved-sym)))
       (swap! ctx update :errors
              (fnil conj [])
              (if (namespace sym)
@@ -128,12 +128,21 @@
 (defn load-alias [ctx alias-dest alias]
   (swap! ctx update :aliases zen.utils/disj-set-union-push alias-dest alias))
 
+(defn load-declare [ctx declare-sym]
+  (swap! ctx update :declares (fnil conj #{}) declare-sym))
+
 (defn symbol-definition? [[k v]]
   (and (symbol? k) (map? v)))
 
 (defn symbol-alias? [[k v]]
   (and (symbol? k) (qualified-symbol? v)))
 
+(defn backward-alias? [[k v]]
+  (and (qualified-symbol? k) (simple-symbol? v)))
+
+(defn backward-alias-declare? [[k v]]
+  (and (simple-symbol? k) (= :zen/declare v)))
+
 (defn pre-load-ns!
   "loads symbols from namespace to ztx before processing"
   [ctx zen-ns ns-map]
@@ -179,11 +188,13 @@
     ;; eval symbols and aliases
     (let [load-result
           (->> (apply dissoc ns-map ['ns 'import 'alias :ns :import :alias])
-               (sort-by (juxt symbol-definition? symbol-alias?)) #_"NOTE: load aliases first, symbols after"
+               (sort-by (juxt symbol-definition? symbol-alias? backward-alias? backward-alias-declare?)) #_"NOTE: load aliases first, symbols after"
                (mapv (fn [[k v :as kv]]
                        (cond (symbol-definition? kv) (load-symbol ctx zen-ns k (merge v opts))
                              (symbol-alias? kv)      (load-alias ctx v (mk-symbol zen-ns k))
-                             :else                   nil)))
+                             (backward-alias? kv)         (load-alias ctx (mk-symbol zen-ns v) k)
+                             (backward-alias-declare? kv) (load-declare ctx (mk-symbol zen-ns k))
+                             :else nil)))
                (mapv (fn [res] (validate-resource ctx res))))]
 
       [:resources-loaded (count load-result)])))

test/zen/alias_test.clj

@@ -164,3 +164,31 @@
           :type "string.type"
           :path [:a]
           :schema [myns/sch2 :a :type]}]})))
+
+
+(deftest backward-alias-test
+  (def test-namespaces
+    '{lib {:ns lib
+           foo :zen/declare
+           bar {:cfg foo}}
+
+      user {:ns     user
+            :import #{lib}
+            lib/foo myfoo
+            myfoo   {:baz :quux}}})
+
+  (def ztx (zen/new-context {:unsafe true :memory-store test-namespaces}))
+
+  (zen/load-ns ztx (get test-namespaces 'user))
+
+  (matcho/match (zen/errors ztx)
+                empty?)
+
+  (matcho/match (zen/get-symbol ztx 'lib/foo)
+                {:baz :quux})
+
+  (matcho/match (zen/get-symbol ztx 'user/myfoo)
+                {:baz :quux})
+
+  (is (= (zen/get-symbol ztx 'lib/foo)
+         (zen/get-symbol ztx 'user/myfoo))))