diff --git a/src/ts/@overflow/commons/core/reflect/class.ts b/src/ts/@overflow/commons/core/reflect/class.ts
index cccc2e4..6918a45 100644
--- a/src/ts/@overflow/commons/core/reflect/class.ts
+++ b/src/ts/@overflow/commons/core/reflect/class.ts
@@ -5,10 +5,13 @@ import {
 } from '@overflow/commons/core/type';
 
 import {AccessibleObject} from './accessible_object';
+import {systemClassRegistry} from './class_registry';
 import {Constructor} from './constructor';
 import {Field} from './field';
 import {Method} from './method';
 
+
+
 export class Class extends AccessibleObject {
   private _clazzType: ClassType;
   private _constructor: Constructor;
@@ -19,17 +22,17 @@ export class Class extends AccessibleObject {
    * forClass
    */
   public static forClass(clazzType: ClassType): Class {
-    return Metadata.get(LOAFER_CLASS, clazzType);
+    return systemClassRegistry.get(clazzType);
   }
 
   /**
    * _defineClass
    */
   public static _defineClass(clazzType: ClassType): Class {
-    let clazz: Class = Metadata.get(LOAFER_CLASS, clazzType);
+    let clazz: Class = Class.forClass(clazzType);
     if (undefined === clazz) {
       clazz = new Class(clazzType);
-      Metadata.set(LOAFER_CLASS, clazz, clazzType);
+      systemClassRegistry.set(clazzType, clazz);
     }
 
     if (null === clazz._constructor) {
@@ -126,10 +129,3 @@ export class Class extends AccessibleObject {
     return null;
   }
 }
-
-/**
- * Metadata key
- * @private
- * @type {string}
- */
-const LOAFER_CLASS = Symbol('loafer:class');
diff --git a/src/ts/@overflow/commons/core/reflect/class_registry.ts b/src/ts/@overflow/commons/core/reflect/class_registry.ts
new file mode 100644
index 0000000..e56534d
--- /dev/null
+++ b/src/ts/@overflow/commons/core/reflect/class_registry.ts
@@ -0,0 +1,11 @@
+import { Registry } from '@overflow/commons/core/util';
+import { ClassType } from '@overflow/commons/core/type';
+import { Class } from './class';
+
+export class ClassRegistry extends Registry<ClassType, Class> {
+  public constructor(parent?: ClassRegistry) {
+    super(parent);
+  }
+}
+
+export const systemClassRegistry = new ClassRegistry();
diff --git a/src/ts/@overflow/commons/core/util/index.ts b/src/ts/@overflow/commons/core/util/index.ts
new file mode 100644
index 0000000..585b667
--- /dev/null
+++ b/src/ts/@overflow/commons/core/util/index.ts
@@ -0,0 +1 @@
+export * from './registry';
diff --git a/src/ts/@overflow/commons/core/util/registry.ts b/src/ts/@overflow/commons/core/util/registry.ts
new file mode 100644
index 0000000..f22cfa9
--- /dev/null
+++ b/src/ts/@overflow/commons/core/util/registry.ts
@@ -0,0 +1,66 @@
+export abstract class Registry<K, V> {
+  private _parent: Registry<K, V>;
+  private _map: Map<K, V>;
+
+  protected constructor(parent?: Registry<K, V>) {
+    this._parent = parent;
+    this._map = new Map<K, V>();
+  }
+
+  public get parent(): Registry<K, V> {
+    return this._parent;
+  }
+
+  public get size(): number {
+    return this._map.size;
+  }
+
+  public get(key: K): V | undefined {
+    let v = this._map.get(key);
+    if (undefined === v && undefined !== this._parent) {
+      v = this._parent.get(key);
+    }
+
+    return v;
+  }
+
+  public has(key: K): boolean {
+    let exist = this._map.has(key);
+    if (!exist && undefined !== this._parent) {
+      exist = this._parent.has(key);
+    }
+    return exist;
+  }
+
+  public set(key: K, value: V): void {
+    this._map.set(key, value);
+  }
+
+  public entries(): IterableIterator<[K, V]> {
+    return this._map.entries();
+  }
+
+  public keys(): IterableIterator<K> {
+    return this._map.keys();
+  }
+
+  public values(): IterableIterator<V> {
+    return this._map.values();
+  }
+
+  public clear(): void {
+    this._map.clear();
+  }
+
+  public delete(key: K): boolean {
+    let result = this._map.delete(key);
+    if (!result && undefined !== this._parent) {
+      result = this._parent.delete(key);
+    }
+    return result;
+  }
+
+  public forEach(callback: (vlaue: V, key: K, map: Map<K, V>) => void, thisArg?: any): void {
+    this._map.forEach(callback, thisArg);
+  }
+}