`cow(obj)` gets; `cow(obj. val)` sets.

README.md

@@ -63,7 +63,8 @@ Useful to "concatenate" a few `subReducer`s. like:
 ## `cowValueModel(key)`
 
 Creates an object with set of functions allowing
-to `set` or `get` specified key from any object.
+to set or get specified key from any object.
+Get when one arg, set when two args.
 You can use dot notation.
 
 Setting return a copy with specified (sub-)property changed;
@@ -72,20 +73,20 @@ in case no change actually happens, returns the original object.
 ```js
     const name = cowValueModel("name");
     
-    name.get({name: "Tom"});
+    name({name: "Tom"});
     // => "Tom"
-    name.set({name: "Tom"}, "Jerry");
+    name({name: "Tom"}, "Jerry");
     // => {name: "Jerry"}
     
     const city = cowValueModel("address.city");
     const object = {address: {city: "New York"}};
     
-    city.get(object);
+    city(object);
     // => "New York"
-    city.set(object, "London");
+    city(object, "London");
     // => {address: {city: "London"}}
     object;
     // => {address: {city: "New York"}}
-    city.set(object, "New York") === object;
+    city(object, "New York") === object;
     // => true
 ```

lib/cow-value-model.js

@@ -23,17 +23,14 @@ var cowValueModel = exports.cowValueModel = function cowValueModel(key) {
         return value === modified ? x : _extends({}, x, _defineProperty({}, key, modified));
     }
 
-    return {
-        key: key,
-        get: function get(obj) {
-            return keys.reduce(function () {
-                var x = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {};
-                var key = arguments[1];
-                return x[key];
-            }, obj);
-        },
-        set: function set(obj, val) {
-            return setField(obj, 0, val);
-        }
+    var GET_SENTINEL = {};
+
+    return function (obj) {
+        var val = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : GET_SENTINEL;
+        return val === GET_SENTINEL ? keys.reduce(function () {
+            var x = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {};
+            var key = arguments[1];
+            return x[key];
+        }, obj) : setField(obj, 0, val);
     };
 };

lib/node.js

@@ -5,31 +5,29 @@ Object.defineProperty(exports, "__esModule", {
 });
 exports.composeReducers = exports.subReducer = exports.cowValueModel = undefined;
 
-var _cowValueModel2 = require("./cow-value-model");
+var _cowValueModel = require("./cow-value-model");
 
 function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr2 = Array(arr.length); i < arr.length; i++) { arr2[i] = arr[i]; } return arr2; } else { return Array.from(arr); } }
 
-exports.cowValueModel = _cowValueModel2.cowValueModel;
+exports.cowValueModel = _cowValueModel.cowValueModel;
 var subReducer = exports.subReducer = function subReducer(key, reducer) {
     for (var _len = arguments.length, otherKeys = Array(_len > 2 ? _len - 2 : 0), _key = 2; _key < _len; _key++) {
         otherKeys[_key - 2] = arguments[_key];
     }
 
-    var _cowValueModel = (0, _cowValueModel2.cowValueModel)(key),
-        getValue = _cowValueModel.get,
-        setValue = _cowValueModel.set,
+    var value = (0, _cowValueModel.cowValueModel)(key),
         otherParts = otherKeys.map(function (each) {
-        return (0, _cowValueModel2.cowValueModel)(each).get;
+        return (0, _cowValueModel.cowValueModel)(each);
     });
 
     return function (state, action) {
-        var newSubState = reducer.apply(undefined, [getValue(state), action].concat(_toConsumableArray(otherParts.map(function (getValue) {
-            return getValue(state);
+        var newSubState = reducer.apply(undefined, [value(state), action].concat(_toConsumableArray(otherParts.map(function (value) {
+            return value(state);
         }))));
         if (typeof newSubState === "undefined") {
             throw new Error("The '" + key + "' reducer must not return undefined.");
         }
-        return setValue(state, newSubState);
+        return value(state, newSubState);
     };
 };
 

src/cow-value-model.js

@@ -7,13 +7,10 @@ export const cowValueModel = (key, keys = key.split('.')) => {
         return value === modified ? x : {...x, [key]: modified};
     }
 
-    return {
-        key,
-        get (obj) {
-            return keys.reduce((x = {}, key) => x[key], obj);
-        },
-        set (obj, val) {
-            return setField(obj, 0, val);
-        }
-    };
+    const GET_SENTINEL = {};
+
+    return (obj, val = GET_SENTINEL) =>
+        val === GET_SENTINEL ?
+            keys.reduce((x = {}, key) => x[key], obj) :
+            setField(obj, 0, val);
 };

src/node.js

@@ -2,15 +2,15 @@ import {cowValueModel} from './cow-value-model';
 export {cowValueModel};
 
 export const subReducer = (key, reducer, ...otherKeys) => {
-    const {get: getValue, set: setValue} = cowValueModel(key),
-        otherParts = otherKeys.map(each => cowValueModel(each).get);
+    const value = cowValueModel(key),
+        otherParts = otherKeys.map(each => cowValueModel(each));
 
     return (state, action) => {
-        let newSubState = reducer(getValue(state), action, ...otherParts.map(getValue => getValue(state)));
+        let newSubState = reducer(value(state), action, ...otherParts.map(value => value(state)));
         if (typeof newSubState === "undefined") {
             throw new Error(`The '${key}' reducer must not return undefined.`);
         }
-        return setValue(state, newSubState);
+        return value(state, newSubState);
     };
 };