READMEを更新

README.md

@@ -1 +1,48 @@
 # Attribute Loader
+
+Attribute Loader wraps [ReflectionAttribute](https://www.php.net/manual/class.reflectionattribute.php).
+
+# How to use
+
+## General
+
+```php
+#[Attribute]
+class FooAttribute {}
+
+#[FooAttribute]
+function target_function(): void {}
+
+$loader = new Fratily\AttributeLoader\AttributeLoader(FooAttribute::class);
+$attributes = $loader->load(new ReflectionFunction('target_function'));
+var_dump($attributes[0]); // object(FooAttribute)
+```
+
+## Custom instance builder
+
+`AttributeLoader::load()` uses `ReflectionAttribute::newInstance()` by default to instantiate.
+However, if you want to interrupt the instantiation process for some reason, you can do the following:
+
+```php
+#[Attribute]
+class FooAttribute {}
+
+#[FooAttribute(name: 'abc')]
+function target_function(int $number): void {}
+
+$loader = new Fratily\AttributeLoader\AttributeLoader(
+    FooAttribute::class,
+    function (ReflectionAttribute $attr) {
+        var_dump($attr->getArguments()); // array('name' => 'abc')
+
+        // do something ...
+        // ex: trigger event / customize attribute arguments ...
+
+        // MUST return an instance of $attr->getName().
+        // MUST not return a subclass of $attr->getName().
+        return new FooAttribute();
+    }
+);
+$attributes = $loader->load(new ReflectionFunction('target_function'));
+var_dump($attributes[0]); // object(FooAttribute)
+```