Package com.singularsys.jep.parser

# Interface Node.HookKey

All Superinterfaces:
  `Serializable`

All Known Implementing Classes:
  `LineNumberingNodeFactory.Numbering`

Enclosing interface:
  `Node`

public static interface Node.HookKey extends Serializable
Nodes can optional have hooks which add meta-data to the node. This meta-data is identified by a HookKey, typically an enum which implements this interface.

Individual instances can be created as enums:

    enum EnumKey implements HookKey { KEY1,KEY2 };

and get and set using `setHook(EnumKey.Key1,3.0)` and `getHook(EnumKey.Key2)`. Alternatively anonymous class can be used:

     public static final HookKey ANON_KEY = new HookKey() {
               private static final long serialVersionUID = 1L;
               private Object readResolve() { return ANON_KEY; }
     };

The `readResolve()` is needed for serialisation.

Since Jep 4.0 HookKey extends `Serializable`.