New middleware, largely untested

src/re_frame/core.cljs

@@ -0,0 +1 @@
+(ns re-frame.core)

src/re_frame/middleware.cljs

@@ -1,34 +1,35 @@
 (ns re-frame.middleware
   (:require
-    [reagent.ratom :refer [IReactiveAtom]]
-    [re-frame.undo :refer [store-now!]]))
+    [reagent.ratom  :refer [IReactiveAtom]]
+    [re-frame.undo  :refer [store-now!]]
+    [re-frame.utils :refer [warn]]))
+
 
-;; -- Middleware Factories -------------------------------------------------------------------------
-;;
 ;; Read this:  https://github.com/Day8/re-frame/wiki/Middleware
-;;
-
-(defn undoable
-  "Middleware which stores an undo checkpoint"
-  [next-handler]
-  (fn handler
-    [app-db event-vec]
-    (store-now!)
-    (next-handler app-db event-vec)))
 
 
 (defn pure
-  "Middleware which allows you to write a pure handler.
-  1. on the way through it extracts the value in the atom
-  2. resets the atom with the returned value after calling the handler"
-  [next-handler]
-  (fn handler
+  "Middleware which adapts a pure handler to the standard calling convension"
+  [handler]
+  (fn new-handler
     [app-db event-vec]
-    (assert (satisfies? IReactiveAtom app-db) "re-frame: make-pure not given a Ratom")
-    (reset! app-db (next-handler @app-db event-vec))))
+    (assert (satisfies? IReactiveAtom app-db)
+            (str "re-frame: pure not given a Ratom" (if (map? app-db) ". Perhaps \"pure\" is in twice.")))
+    (reset! app-db (handler @app-db event-vec))))
 
 
-;; example of applying
+(defn undoable
+  "Middleware which stores an undo checkpoint, prior to handler being called."
+  [handler]
+  (fn new-handler
+    [app-db event-vec]
+    (store-now!)
+    (handler app-db event-vec)))
+
+
+
+
+;; check the state of db AFTER the handler has run, using a prismatic Schema.
 #_(defn check-schema
 "Middleware for checking that a handlers mutations leave the state in a schema-matching way"
 [a-prismatic-schema]
@@ -39,19 +40,54 @@
     (let [val    (next-handler db v)
           valid? true]   ;; XXXXX  replace true by code which checks the schema using original parameter
       (if (not valid?)
-        (warn "re-frame: schema not valid after:" ))
+        (warn "re-frame: schema not valid after:" v))
       val))))
 
 
+(defn apply-event
+  "Middleware which removes the first bit of v, and \"expands\" other parameters.
+  Normally handlers get two paramters:  db and v.
+  With this middleware, if v was [:id 1 2], the handler would be called with db, 1, 2.
+  Use the middleware in the very last place -- right-most in  comp"
+  [handler]
+  (fn new-handler
+    [db v]
+    (apply handler (cons db (rest v)))))
+
+
+(defn path
+  "Supplies a sub-tree of `app-db` to the handler.
+  Assumes pure is
+  Grafts the result back into."
+  [p]
+  (fn middleware
+    [handler]
+    (fn new-handler
+      [db v]
+      (warn (vector? p) "re-frame: ex")
+      (assoc-in db p (handler db v)))))
+
+
 (defn validate
   "Middleware that applies a validation function to the db after the handler is finished.
 The validation function f, might assoc warnings and errors to the new state, created by the handler.
 By validation, I mean validation of what the user has entered, or the state they have taken the app too"
   [f]
   (fn middleware
-    [next-handler]
-    (fn handler
+    [handler]
+    (fn new-handler
       [db v]
-      (f (next-handler db v)))))
+      (f (handler db v)))))
+
+
+(defn log-events
+  "Middleware that logs events (vec) using to the given logger fucntion"
+  [logger]
+  (fn middleware
+    [handler]
+    (fn new-handler
+      [db v]
+      (logger v)
+      (handler db v))))