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packages/initialize/README.md

+# Initialize [![Build Status](https://travis-ci.org/dart-lang/initialize.svg?branch=master)](https://travis-ci.org/dart-lang/initialize)
+
+This package provides a common interface for initialization annotations on top
+level methods, classes, and libraries. The interface looks like this:
+
+```dart
+abstract class Initializer<T> {
+  dynamic initialize(T target);
+}
+```
+
+The `initialize` method will be called once for each annotation. The type `T` is
+determined by what was annotated. For libraries it will be a `LibraryIdentifier`
+representing that library, for a class it will be the `Type` representing that
+class, and for a top level method it will be the `Function` object representing
+that method.
+
+If a future is returned from the initialize method, it will wait until the future
+completes before running the next initializer.
+
+## Usage
+
+### @initMethod
+
+There is one initializer which comes with this package, `@initMethod`. Annotate
+any top level function with this and it will be invoked automatically. For
+example, the program below will print `hello`:
+
+```dart
+import 'package:initialize/initialize.dart';
+
+@initMethod
+printHello() => print('hello');
+
+main() => run();
+```
+
+### Running the initializers
+
+In order to run all the initializers, you need to import
+`package:initialize/initialize.dart` and invoke the `run` method. This should
+typically be the first thing to happen in your main. That method returns a Future,
+so you should put the remainder of your program inside the chained then call.
+
+```dart
+import 'package:initialize/initialize.dart';
+
+main() {
+  run().then((_) {
+    print('hello world!');
+  });
+}
+```
+
+## Transformer
+
+During development a mirror based system is used to find and run the initializers,
+but for deployment there is a transformer which can replace that with a static list
+of initializers to be ran.
+
+This will create a new entry point which bootstraps your existing app, this will
+have the same file name except `.dart` with be replaced with `.initialize.dart`.
+If you supply an html file to `entry_points` then it will bootstrap the dart
+script tag on that page and replace the `src` attribute to with the new
+bootstrap file.
+
+Below is an example pubspec with the transformer:
+
+    name: my_app
+    dependencies:
+      initialize: any
+    transformers:
+    - initialize:
+        entry_points: web/index.html
+
+## Creating your own initializer
+
+Lets look at a slightly simplified version of the `@initMethod` class:
+
+```dart
+class InitMethod implements Initializer<Function> {
+  const InitMethod();
+
+  @override
+  initialize(Function method) => method();
+}
+```
+
+You would now be able to add `@InitMethod()` in front of any function and it
+will be automatically invoked when the user calls `run()`.
+
+For classes which are stateless, you can usually just have a single const
+instance, and that is how the actual InitMethod implementation works. Simply add
+something like the following:
+
+```dart
+const initMethod = const InitMethod();
+```
+
+Now when people use the annotation, it just looks like `@initMethod` without any
+parenthesis, and its a bit more efficient since there is a single instance. You
+can also make your class private to force users into using the static instance.
+
+## Creating custom transformer plugins
+
+It is possible to create a custom plugin for the initialize transformer which
+allows you to have full control over what happens to your annotations at compile
+time. Implement `InitializerPlugin` class and pass that in to the
+`InitializeTransformer` to make it take effect.
+
+You will need to be familiar with the `analyzer` package in order to write these
+plugins, but they can be extremely powerful. See the `DefaultInitializerPlugin`
+in `lib/build/initializer_plugin.dart` as a reference. Chances are you may want
+to extend that class in order to get a lot of the default functionality.