Added documentation for @ExtensionMethod feature

8 files changed, 161 insertions, 2 deletions

diff --git a/buildScripts/website.ant.xml b/buildScripts/website.ant.xml
index 8397185a..0531129d 100644
--- a/buildScripts/website.ant.xml
+++ b/buildScripts/website.ant.xml
@@ -148,6 +148,9 @@ such as converting the changelog into HTML, and creating javadoc.
 		<antcall target="-integrateSnippet">
 			<param name="transformationName" value="experimental/Accessors" />
 		</antcall>
+		<antcall target="-integrateSnippet">
+			<param name="transformationName" value="experimental/ExtensionMethod" />
+		</antcall>
 	</target>
 	
 	<target name="-website-dist">
diff --git a/doc/changelog.markdown b/doc/changelog.markdown
index e59a43c7..ec79ead7 100644
--- a/doc/changelog.markdown
+++ b/doc/changelog.markdown
@@ -2,6 +2,8 @@ Lombok Changelog
 ----------------
 
 ### v0.11.1 (EDGE)
+* FEATURE: {Experimental} `@ExtensionMethod` is now available to add extensions to
+any type in the form of static methods that take as first parameter an object of that type. [Documentation on @ExtensionMethod](http://projectlombok.org/features/experimental/ExtensionMethod.html)
 * ENHANCEMENT: Small performance enhancements in `equals` and `hashCode`. [Issue #366](http://code.google.com/p/projectlombok/issues/detail?id=366)
 * BUGFIX: Eclipse refactor script 'rename method arguments' should work more often with lombok-affected methods.
 * BUGFIX: Using 'val' in an enhanced for loop did not work if the iterable was a raw type.
diff --git a/usage_examples/experimental/AccessorsExample_pre.jpage b/usage_examples/experimental/AccessorsExample_pre.jpage
index ef063daa..f1591aba 100644
--- a/usage_examples/experimental/AccessorsExample_pre.jpage
+++ b/usage_examples/experimental/AccessorsExample_pre.jpage
@@ -1,4 +1,4 @@
-import lombok.Accessors;
+import lombok.experimental.Accessors;
 import lombok.Getter;
 import lombok.Setter;
 
diff --git a/usage_examples/experimental/ExtensionMethodExample_post.jpage b/usage_examples/experimental/ExtensionMethodExample_post.jpage
new file mode 100644
index 00000000..72a838bd
--- /dev/null
+++ b/usage_examples/experimental/ExtensionMethodExample_post.jpage
@@ -0,0 +1,20 @@
+public class ExtensionMethodExample {
+	public String test() {
+		int[] intArray = {5, 3, 8, 2};
+		java.util.Arrays.sort(intArray);
+		
+		String iAmNull = null;
+		return Extensions.or(iAmNull, Extensions.toTitleCase("hELlO, WORlD!"));
+	}
+}
+
+class Extensions {
+	public static <T> T or(T obj, T ifNull) {
+		return obj != null ? obj : ifNull;
+	}
+	
+	public static String toTitleCase(String in) {
+		if (in.isEmpty()) return in;
+		return "" + Character.toTitleCase(in.charAt(0)) + in.substring(1).toLowerCase();
+	}
+}
diff --git a/usage_examples/experimental/ExtensionMethodExample_pre.jpage b/usage_examples/experimental/ExtensionMethodExample_pre.jpage
new file mode 100644
index 00000000..26d0ee38
--- /dev/null
+++ b/usage_examples/experimental/ExtensionMethodExample_pre.jpage
@@ -0,0 +1,23 @@
+import lombok.experimental.ExtensionMethod;
+
+@ExtensionMethod({java.util.Arrays.class, Extensions.class})
+public class ExtensionMethodExample {
+	public String test() {
+		int[] intArray = {5, 3, 8, 2};
+		intArray.sort();
+		
+		String iAmNull = null;
+		return iAmNull.or("hELlO, WORlD!".toTitleCase());
+	}
+}
+
+class Extensions {
+	public static <T> T or(T obj, T ifNull) {
+		return obj != null ? obj : ifNull;
+	}
+	
+	public static String toTitleCase(String in) {
+		if (in.isEmpty()) return in;
+		return "" + Character.toTitleCase(in.charAt(0)) + in.substring(1).toLowerCase();
+	}
+}
diff --git a/website/features/experimental/Accessors.html b/website/features/experimental/Accessors.html
index 65b3c3b6..f3a7878f 100644
--- a/website/features/experimental/Accessors.html
+++ b/website/features/experimental/Accessors.html
@@ -84,7 +84,7 @@
 			</div>
 		</div>
 		<div class="footer">
-			<a href="index.html">Back to experimental features</a> | <span class="disabled">Previous feature</span> | <span class="disabled">Next feature</span><br />
+			<a href="index.html">Back to experimental features</a> | <span class="disabled">Previous feature</span> | <a href="ExtensionMethod.html">Next feature (@ExtensionMethod)</a><br />
 			<a href="../../credits.html" class="creditsLink">credits</a> | <span class="copyright">Copyright &copy; 2009-2012 The Project Lombok Authors, licensed under the <a href="http://www.opensource.org/licenses/mit-license.php">MIT license</a>.</span>
 		</div>
 		<div style="clear: both;"></div>
diff --git a/website/features/experimental/ExtensionMethod.html b/website/features/experimental/ExtensionMethod.html
new file mode 100644
index 00000000..773904bb
--- /dev/null
+++ b/website/features/experimental/ExtensionMethod.html
@@ -0,0 +1,109 @@
+<!DOCTYPE html>
+<html><head>
+	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
+	<link rel="stylesheet" type="text/css" href="../../logi/reset.css" />
+	<link rel="stylesheet" type="text/css" href="../features.css" />
+	<link rel="shortcut icon" href="../../favicon.ico" type="image/x-icon" />
+	<meta name="description" content="Spice up your java" />
+	<title>EXPERIMENTAL - @ExtensionMethod</title>
+</head><body><div id="pepper">
+	<div class="minimumHeight"></div>
+	<div class="meat">
+		<div class="header"><a href="../../index.html">Project Lombok</a></div>
+		<h1>@ExtensionMethod</h1>
+		<div class="byline">Annoying API? Fix it yourself: Add new methods to existing types!</div>
+		<div class="since">
+			<h3>Since</h3>
+			<p>
+				@ExtensionMethod was introduced as experimental feature in lombok v0.11.2.
+			</p>
+		</div>
+		<div class="experimental">
+			<h3>Experimental</h3>
+			<p>
+			Experimental because:
+			<ul>
+				<li>High-impact on code style</li>
+				<li>Really would like to ship with utility methods to expand common classes, but so far lombok doesn't have a good distribution method for such runtime dependencies</li>
+				<li>Affects quite a bit of eclipse, and auto-complete e.d. do not work yet in netbeans</li>
+				<li>Should @ExtensionMethod be legal on methods? Should it be legal on packages?</li>
+			</ul>
+			Current status: <em>positive</em> - Currently we feel this feature may move out of experimental status with no or minor changes soon.
+		</div>
+		<div class="overview">
+			<h3>Overview</h3>
+			<p>
+				You can make a class containing a bunch of <code>public</code>, <code>static</code> methods which all take at least 1
+				parameter. These methods will extend the type of the first parameter, as if they were instance methods, using the
+				<code>@ExtensionMethod</code> feature.
+			</p>
+			</p><p>
+				For example, if you create <code>public static String toTitleCase(String in) { ... }</code>, you can use the
+				<code>@ExtensionMethod</code> feature to make it look like the <code>java.lang.String</code> class has a method named
+				<code>toTitleCase</code>, which has no arguments. The first argument of the static method fills the role of <code>this</code>
+				in instance methods.
+			</p><p>
+				All methods that are <code>public</code>, <code>static</code>, and have at least 1 argument whose type is not primitive, are
+				considered extension methods, and each will be injected into the namespace of the type of the first parameter as if they were
+				instance methods. As in the above example, a call that looks like: <code>foo.toTitleCase()</code> is replaced with
+				<code>ClassContainingYourExtensionMethod.toTitleCase(foo);</code>. Note that it is actually not an instant
+				<code>NullPointerException</code> if <code>foo</code> is null - it is passed like any other parameter.
+			</p><p>
+				You can pass any number of classes to the <code>@ExtensionMethod</code> annotation; they will all be searched for
+				extension methods. These extension methods apply for any code that is in the annotated class.
+			</p><p>
+				Lombok does not (currently) have any runtime dependencies which means lombok does not (currently) ship with any useful
+				extension methods so you'll have to make your own. However, here's one that might spark your imagination:
+				<pre>public class ObjectExtensions {
+	public static &lt;T&gt; or(T object, T ifNull) {
+		return object != null ? object : ifNull;
+	}
+}</pre>
+			With the above class, if you add <code>@ExtensionMethod(ObjectExtensions.class)</code> to your class definition, you can write:
+			<pre>String x = null;
+System.out.println(x.or("Hello, World!"));</pre>
+			The above code will not fail with a <code>NullPointerException</code>; it will actually output <code>Hello, World!</code>
+			</p>
+		</div>
+		<div class="snippets">
+			<div class="pre">
+				<h3>With Lombok</h3>
+				<div class="snippet">@HTML_PRE@</div>
+			</div>
+			<div class="sep"></div>
+			<div class="post">
+				<h3>Vanilla Java</h3>
+				<div class="snippet">@HTML_POST@</div>
+			</div>
+		</div>
+		<div style="clear: left;"></div>
+		<div class="overview">
+			<h3>Small print</h3><div class="smallprint">
+				<p>
+					Calls are rewritten to a call to the extension method; the static method itself is not inlined. Therefore, the 
+					extension method must be present both at compile and at runtime.
+				</p><p>
+					Generics is fully applied to figure out extension methods. i.e. if the first parameter of your extension method is
+					<code>List&lt;? extends String&gt;</code>, then any expression that is compatible with that will have your extension method,
+					but other kinds of lists won't. So, a <code>List&lt;Object&gt;</code> won't get it, but a <code>List&lt;String&gt;</code> will.
+				</p>
+			</div>
+		</div>
+		<div class="footer">
+			<a href="index.html">Back to experimental features</a> | <a href="Accessors.html">Previous feature (@Accessors)</a> | <span class="disabled">Next feature</a><br />
+			<a href="../../credits.html" class="creditsLink">credits</a> | <span class="copyright">Copyright &copy; 2009-2012 The Project Lombok Authors, licensed under the <a href="http://www.opensource.org/licenses/mit-license.php">MIT license</a>.</span>
+		</div>
+		<div style="clear: both;"></div>
+	</div>
+</div>
+<script type="text/javascript">
+	var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www.");
+	document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E"));
+</script>
+<script type="text/javascript">
+	try {
+		var pageTracker = _gat._getTracker("UA-9884254-1");
+		pageTracker._trackPageview();
+	} catch(err) {}
+</script>
+</body></html>
diff --git a/website/features/experimental/index.html b/website/features/experimental/index.html
index e4e90c41..9b25d710 100644
--- a/website/features/experimental/index.html
+++ b/website/features/experimental/index.html
@@ -24,6 +24,8 @@
 			<dl>
 				<dt><a href="Accessors.html"><code>@Accessors</code></a></dt>
 				<dd>A more fluent API for getters and setters.</dd>
+				<dt><a href="ExtensionMethod.html"><Code>@ExtensionMethod</code></a></dt>
+				<dd>Annoying API? Fix it yourself: Add new methods to existing types!</dd>
 			</dl>
 		</div>
 		<div class="footer">