[new] Refactor tools ns, embed dynamic *freeze-opts* in wrappers

src/taoensso/nippy/tools.clj

@@ -1,60 +1,74 @@
 (ns taoensso.nippy.tools
-  "Utils for 3rd-party tools that want to add user-configurable Nippy support.
+  "Utils for community tools that want to add user-configurable Nippy support.
   Used by Carmine, Faraday, etc."
   (:require [taoensso.nippy :as nippy]))
 
 (def ^:dynamic *freeze-opts* nil)
 (def ^:dynamic *thaw-opts*   nil)
 
-(defmacro with-freeze-opts [opts & body] `(binding [*freeze-opts* ~opts] ~@body))
-(defmacro with-thaw-opts   [opts & body] `(binding [*thaw-opts*   ~opts] ~@body))
+(defn ^:no-doc -merge-opts
+  "Private, implementation detail."
+  ([x y  ] (if x (conj x y) y))
+  ([x y z] (-merge-opts (-merge-opts x y) z)))
+
+(do
+  (defmacro with-freeze-opts  [opts & body] `(binding [*freeze-opts*                            ~opts ] ~@body))
+  (defmacro with-freeze-opts+ [opts & body] `(binding [*freeze-opts* (-merge-opts *freeze-opts* ~opts)] ~@body))
+  (defmacro with-thaw-opts    [opts & body] `(binding [*thaw-opts*                              ~opts ] ~@body))
+  (defmacro with-thaw-opts+   [opts & body] `(binding [*thaw-opts*   (-merge-opts *thaw-opts*   ~opts)] ~@body)))
 
 (deftype WrappedForFreezing [val opts])
 (defn wrapped-for-freezing? [x] (instance? WrappedForFreezing x))
-(defn    wrap-for-freezing
-  "Ensures that given arg (any freezable data type) is wrapped so that
-  (tools/freeze <wrapped-arg>) will serialize as
-  (nippy/freeze <unwrapped-arg> <opts>).
-
-  See also `nippy.tools/freeze`, `nippy.tools/thaw`."
-  ([x     ] (wrap-for-freezing x nil))
-  ([x opts]
-   (if (instance? WrappedForFreezing x)
-     (let [^WrappedForFreezing x x]
-       (if (= (.-opts x) opts)
-         x
-         (WrappedForFreezing. (.-val x) opts)))
-     (WrappedForFreezing.            x  opts))))
-
-(defn freeze
-  "Like `nippy/freeze` but uses as opts the following merged in order of
-  ascending preference:
-
-    - Optional `default-opts` arg given to this fn  (default nil).
-    - Optional `*freeze-opts*` dynamic value        (default nil).
-    - Optional opts provided to `wrap-for-freezing` (default nil)."
-
-  ([x             ] (freeze x nil))
-  ([x default-opts]
-   (let [default-opts (get default-opts :default-opts default-opts) ; For back compatibility
-         merged-opts  (conj (or default-opts {}) *freeze-opts*)]
-
-     (if (instance? WrappedForFreezing x)
-       (let [^WrappedForFreezing x x]
-         (nippy/freeze (.-val x) (conj merged-opts (.-opts x))))
-       (nippy/freeze          x        merged-opts)))))
-
-(defn thaw
-  "Like `nippy/thaw` but uses as opts the following merged in order of
-  ascending preference:
-
-    - Optional `default-opts` arg given to this fn  (default nil).
-    - Optional `*thaw-opts*` dynamic value          (default nil)."
-
-  ([ba             ] (thaw ba nil))
-  ([ba default-opts]
-   (let [default-opts (get default-opts :default-opts default-opts) ; For back compatibility
-         merged-opts  (conj (or default-opts {}) *thaw-opts*)]
-     (nippy/thaw ba merged-opts))))
+
+(let [-merge-opts -merge-opts]
+  (defn wrap-for-freezing
+    "Captures (merge `tools/*thaw-opts*` `wrap-opts`), and returns
+    the given argument in a wrapped form so that `tools/freeze` will
+    use the captured options when freezing the wrapper argument.
+
+    See also `tools/freeze`."
+    ([x          ] (wrap-for-freezing x nil))
+    ([x wrap-opts]
+     (let [captured-opts (-merge-opts *freeze-opts* wrap-opts)] ; wrap > dynamic
+       (if (instance? WrappedForFreezing x)
+         (let [^WrappedForFreezing x x]
+           (if (= (.-opts x) captured-opts)
+             x
+             (WrappedForFreezing. (.-val x) captured-opts)))
+         (WrappedForFreezing.            x  captured-opts))))))
+
+(let [-merge-opts -merge-opts]
+  (defn freeze
+    "Like `nippy/freeze` but uses as options the following, merged in
+    order of ascending preference:
+
+      1. `default-opts` given to this fn            (default nil).
+      2. `tools/*freeze-opts*` dynamic value        (default nil).
+      3. Opts captured by `tools/wrap-for-freezing` (default nil).
+
+    See also `tools/wrap-for-freezing`."
+    ([x             ] (freeze x nil))
+    ([x default-opts]
+     (let [default-opts (get default-opts :default-opts default-opts) ; Back compatibility
+           active-opts  (-merge-opts default-opts *freeze-opts*)] ; dynamic > default
+
+       (if (instance? WrappedForFreezing x)
+         (let [^WrappedForFreezing x x]
+           (nippy/freeze (.-val x) (-merge-opts active-opts (.-opts x)))) ; captured > active!
+         (nippy/freeze          x               active-opts))))))
+
+(let [-merge-opts -merge-opts]
+  (defn thaw
+    "Like `nippy/thaw` but uses as options the following, merged in
+    order of ascending preference:
+
+      1. `default-opts` given to this fn   (default nil).
+      2. `tools/*thaw-opts*` dynamic value (default nil)."
+    ([ba             ] (thaw ba nil))
+    ([ba default-opts]
+     (let [default-opts (get default-opts :default-opts default-opts) ; Back compatibility
+           active-opts  (-merge-opts default-opts *thaw-opts*)] ; dynamic > default
+
+       (nippy/thaw ba active-opts)))))
 
 (comment (thaw (freeze (wrap-for-freezing "wrapped"))))