From 90c9c69ff0b84633674f7f32f0abc141da0820fd Mon Sep 17 00:00:00 2001
From: Sam Stephenson <sam@37signals.com>
Date: Mon, 30 Jul 2007 04:38:20 +0000
Subject: [PATCH] prototype: Add Function#argumentNames, which returns an
 ordered array of the function's named arguments.

---
 CHANGELOG           | 2 ++
 src/base.js         | 5 +++++
 test/unit/base.html | 7 +++++++
 3 files changed, 14 insertions(+)

diff --git a/CHANGELOG b/CHANGELOG
index 43db9e1..00ed9d3 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Add Function#argumentNames, which returns an ordered array of the function's named arguments.  [sam]
+
 * Add Prototype.Browser.MobileSafari which evaluates to true on the iPhone's browser.  [sam]
 
 * Optimize Selector#match and Element#match for simple selectors.  Closes #9082.  [Andrew Dupont]
diff --git a/src/base.js b/src/base.js
index 143aa4c..c89aa55 100644
--- a/src/base.js
+++ b/src/base.js
@@ -79,6 +79,11 @@ Object.extend(Object, {
 });
 
 Object.extend(Function.prototype, {
+  argumentNames: function() {
+    var names = this.toString().match(/^function\s*\((.*?)\)/)[1].split(",").invoke("strip");
+    return names.length == 1 && !names[0] ? [] : names;
+  },
+  
   bind: function() {
     if (arguments.length < 2 && arguments[0] === undefined) return this;
     var __method = this, args = $A(arguments), object = args.shift();
diff --git a/test/unit/base.html b/test/unit/base.html
index fb0b210..97fe526 100644
--- a/test/unit/base.html
+++ b/test/unit/base.html
@@ -56,6 +56,13 @@
     
   new Test.Unit.Runner({
     
+    testFunctionArgumentNames: function() { with(this) {
+      assertEnumEqual([], (function() {}).argumentNames());
+      assertEnumEqual(["one"], (function(one) {}).argumentNames());
+      assertEnumEqual(["one", "two", "three"], (function(one, two, three) {}).argumentNames());
+      assertEqual("$super", (function($super) {}).argumentNames().first());
+    }},
+    
     testFunctionBind: function() { with(this) {
       function methodWithoutArguments() { return this.hi };
       function methodWithArguments()    { return this.hi + ',' + $A(arguments).join(',') };