Implement P.props

README.md

@@ -17,6 +17,7 @@ Additional examples are available in [tests](tests).
 	- [`method(Function method)`](#methodfunction-method)
 	- [`fromCallback(Function callback)`](#fromcallbackfunction-callback)
 	- [`defer(Function fn)`](#deferfunction-fn)
+	- [`props(Object obj)`](#propsobject-obj)
 	- [`extend(Promise)`](#extendpromise)
 * [Instance Methods](#instance-methods)
 	- [`return(value)`](#returnvalue)
@@ -146,6 +147,35 @@ deferred.promise.catch(console.error);
 deferred.reject(new Error("Goodbye, World!"));
 ```
 
+#### `props(Object obj)`
+
+Accepts an object and waits for all promise values to resolve before returning. Returns
+a new object with values from the resolved promises.
+
+```js
+const P = require("extends-promise");
+
+P
+	.props({
+		x : P.delay(100, 'a'),
+		y : P.delay(50, 'b'),
+		z : 'c'
+	})
+	.then(res => console.log(res.x));
+```
+
+This method can be especially helpful when combined with destructuring as a way of returning
+named tuples.
+
+```js
+P
+	.props({
+		x : P.delay(100, 'a'),
+		y : 'b'
+	})
+	.then(({ x, y }) => console.log(`x: ${x}, y: ${y}`));
+```
+
 #### `extend(Promise)`
 
 Extend a promise implementation with methods in this library. Useful if you want

index.js

@@ -114,6 +114,16 @@ class P extends Promise {
 		return p.forEach(fn);
 	}
 
+	static props(o) {
+		const keys = Object.keys(o);
+
+		return P
+			.map(keys, k => o[k])
+			.then(res => res.reduce((y, x, i) => Object.assign(y, {
+				[keys[i]] : x
+			}), {}));
+	}
+
 	static promisify(fn, ctx) {
 		return function promisifedMethod() {
 			return new P((resolve, reject) => {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "extends-promise",
-  "version": "1.3.0",
+  "version": "1.4.0",
   "description": "Micro-library that extends native promises",
   "main": "index.js",
   "engines": {
@@ -30,11 +30,11 @@
   "homepage": "https://github.com/kjvalencik/extends-promise#readme",
   "devDependencies": {
     "eslint-config-airbnb-base": "^3.0.1",
-    "eslint-plugin-import": "^1.8.0",
+    "eslint-plugin-import": "^1.9.0",
     "gulp": "^3.9.1",
     "gulp-coveralls": "^0.1.4",
     "gulp-eslint": "^2.0.0",
-    "gulp-istanbul": "^0.10.4",
+    "gulp-istanbul": "^1.0.0",
     "gulp-mocha": "^2.2.0"
   }
 }

tests/helpers.test.js

@@ -84,14 +84,14 @@ describe("Helpers", () => {
 	});
 
 	describe(".tap", () => {
-		it(".tap: should be able to call then without affecting chain", () => {
+		it("should be able to call then without affecting chain", () => {
 			return P
 				.resolve(1)
 				.tap(() => 2)
 				.then(res => assert.strictEqual(res, 1));
 		});
 
-		it(".tap: should wait for returned promise to resolve", () => {
+		it("should wait for returned promise to resolve", () => {
 			let waited = false;
 
 			return P
@@ -105,4 +105,30 @@ describe("Helpers", () => {
 				.then(() => assert.strictEqual(waited, true));
 		});
 	});
+
+	describe(".props", () => {
+		it("should wait for promise values to reolve", () => {
+			return P
+				.props({
+					x : P.delay(1, 'a'),
+					y : P.delay(5, 'b')
+				})
+				.then(res => assert.deepEqual(res, {
+					x : 'a',
+					y : 'b'
+				}));
+		});
+
+		it("should allow non-promise keys", () => {
+			return P
+				.props({
+					x : P.delay(1, 'a'),
+					y : 'b'
+				})
+				.then(res => assert.deepEqual(res, {
+					x : 'a',
+					y : 'b'
+				}));
+		});
+	});
 });