Allow freeze, thaw opts to override bindings

src/taoensso/nippy.clj

@@ -994,14 +994,46 @@
     (with-cache (-freeze-with-meta! x dos))
     (.toByteArray baos)))
 
+(defn- call-with-bindings
+  "Allow opts to override config bindings. Undocumented."
+  [opts f]
+  (let [opt->bindings
+        (fn [bindings id var]
+          (if-let [o (find opts id)]
+            (assoc bindings var (val o))
+            (do    bindings)))
+
+        bindings
+        (-> nil
+          (opt->bindings :freeze-fallback        #'*freeze-fallback*)
+          (opt->bindings :auto-freeze-compressor #'*auto-freeze-compressor*)
+          (opt->bindings :custom-readers         #'*custom-readers*))]
+
+    (if-not bindings
+      (f) ; Common case
+      (try
+        (push-thread-bindings bindings)
+        (f)
+        (finally
+          (pop-thread-bindings))))))
+
+(comment
+  (enc/qb 1e4
+    (call-with-bindings {}                       (fn [] *freeze-fallback*))
+    (call-with-bindings {:freeze-fallback "foo"} (fn [] *freeze-fallback*))))
+
 (defn freeze
   "Serializes arg (any Clojure data type) to a byte array. To freeze custom
   types, extend the Clojure reader or see `extend-freeze`."
   ([x] (freeze x nil))
-  ([x {:keys [compressor encryptor password]
+  ([x {:as   opts
+       :keys [compressor encryptor password]
        :or   {compressor :auto
-              encryptor  aes128-gcm-encryptor}
+              encryptor  aes128-gcm-encryptor}}]
-       :as   opts}]
+
+   (call-with-bindings opts
+     (fn []
+
        (let [;; Intentionally undocumented:
              no-header? (or (get opts :no-header?)
                           (get opts :skip-header?))
@@ -1052,7 +1084,7 @@
                     (when-let [e encryptor]
                       (or (encryption/standard-header-ids
                             (encryption/header-id e))
-                       :else))}))))))))
+                        :else))}))))))))))
 
 ;;;; Thawing
 
@@ -1388,14 +1420,17 @@
 
   ([ba] (thaw ba nil))
   ([^bytes ba
-    {:keys [v1-compatibility? compressor encryptor password]
+    {:as   opts
+     :keys [v1-compatibility? compressor encryptor password]
      :or   {compressor :auto
-            encryptor  :auto}
+            encryptor  :auto}}]
-     :as   opts}]
 
    (assert (not (get opts :headerless-meta))
      ":headerless-meta `thaw` opt removed in Nippy v2.7+")
 
+   (call-with-bindings opts
+     (fn []
+
        (let [v2+?       (not v1-compatibility?)
              no-header? (get opts :no-header?) ; Intentionally undocumented
              ex (fn ex
@@ -1461,7 +1496,7 @@
              ;; Well-formed header definitely not present
              (if v2+?
                (ex err-msg-unknown-thaw-failure)
-           (thaw-v1-data ba (fn [_] (ex err-msg-unknown-thaw-failure)))))))))
+               (thaw-v1-data ba (fn [_] (ex err-msg-unknown-thaw-failure)))))))))))
 
 (comment
   (thaw (freeze "hello"))