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| |
| = DevFaqLookupCookie |
| :jbake-type: wiki |
| :jbake-tags: wiki, devfaq, needsreview |
| :jbake-status: published |
| :keywords: Apache NetBeans wiki DevFaqLookupCookie |
| :description: Apache NetBeans wiki DevFaqLookupCookie |
| :toc: left |
| :toc-title: |
| :syntax: true |
| |
| === What is the difference between getCookie(Class), SharedClassObject.get(Class) and Lookup.lookup(Class)? |
| |
| All of these are really historical variations on the same theme. In all cases, you pass a `Class` object and get back null or an instance of that class. You can see the progression in genericness: |
| |
| `SharedClassObject` is the oldest version of the Lookup pattern in NetBeans APIs, dating to circa 1997 (because of various performance issues, eventually all usages of `SharedClassObject` should be deprecated and removed from the APIs). You'll see that form used in `SystemOption` for storing settings, and most of the singleton Action objects in the actions API. All objects returned by it will be instances of `SharedClassObject`. |
| |
| `getCookie()` (circa 1999) is specific to link:DevFaqWhatIsANode.asciidoc[Node]s and link:DevFaqDataObject.asciidoc[DataObject]s. It uses the same pattern, but all objects returned by it will implement the empty `Node.Cookie` marker interface. |
| |
| The down-side to both of the above is that they specify the return type. In the case of `Node.Cookie`, in practice, this meant that anything that might possibly need to be provided by a `DataObject` or `Node` needed to implement this silly marker interface, forcing it to have a dependency on the Nodes API, or a wrapper Cookie class had to be created to provide the underlying object, which just added useless classes and noise. |
| |
| link:DevFaqLookup.asciidoc[Lookup] is the most modern and generic version of this pattern, and probably the final one. It offers two advantages: |
| |
| 1. Its return type is `java.lang.Object`, so it can be used directly with anything |
| 2. Having objects _own_ a lookup rather than directly providing a `lookup(Class c)` method makes it easier to replace or proxy the Lookup of some object |
| |
| === Apache Migration Information |
| |
| The content in this page was kindly donated by Oracle Corp. to the |
| Apache Software Foundation. |
| |
| This page was exported from link:http://wiki.netbeans.org/DevFaqLookupCookie[http://wiki.netbeans.org/DevFaqLookupCookie] , |
| that was last modified by NetBeans user Admin |
| on 2009-11-06T15:51:49Z. |
| |
| |
| *NOTE:* This document was automatically converted to the AsciiDoc format on 2018-02-07, and needs to be reviewed. |
