com.diffplug.common.base

Class DurianPlugins

java.lang.Object

com.diffplug.common.base.DurianPlugins

public class DurianPlugins
extends java.lang.Object

A registry for plugin implementations which obeys the following contract: Once someone has requested a class from DurianPlugins, whatever instance was returned will continue to be returned for every future call. This gives the impression of a global constant. Before the value has been requested, it can be set programmatically or by setting a system property, which allows configuring a system or framework appropriate behavior. This eternal instance is determined by: - the first call to register(Class pluginClass, T pluginImpl) - if a system property named "durian.plugins.{pluginClass.getCanonicalName()}" is set to the fully-qualified name of an implementation class with a no-argument constructor, then an instance of that class will be instantiated and used as the plugin implementation - the defaultImpl that was specified in the first call to get() This class was inspired by RxJava's RxJavaPlugins. Many thanks to them!

Method Summary

Modifier and Type	Method and Description
static <T> T	get(java.lang.Class<T> pluginClass, T defaultImpl) Returns an instance of pluginClass which is guaranteed to be identical throughout the runtime existence of this library.
static <T> void	register(java.lang.Class<T> pluginClass, T pluginImpl) Registers an implementation as a global override of any injected or default implementations.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

register

public static <T> void register(java.lang.Class<T> pluginClass,
                                T pluginImpl)
                         throws java.lang.IllegalStateException

Registers an implementation as a global override of any injected or default implementations.

Parameters:

pluginClass - The interface which is being registered.

pluginImpl - The implementation of that interface which is being registered.

Throws:

java.lang.IllegalStateException - If called more than once or if a value has already been requested.

get

public static <T> T get(java.lang.Class<T> pluginClass,
                        T defaultImpl)

Returns an instance of pluginClass which is guaranteed to be identical throughout the runtime existence of this library. The returned instance is determined by: - the first call to register(Class pluginClass, T pluginImpl) - if a system property named "durian.plugins.{pluginClass.getCanonicalName()}" is set to the fully-qualified name of an implementation class with a no-argument constructor, then an instance of that class will be instantiated and used as the plugin implementation - the defaultImpl that was specified in the first call to get()

Parameters:

pluginClass - The interface which is being requested.

defaultImpl - A default implementation of that interface.

Returns:

An instance of pluginClass, which is guaranteed to be returned for every future request for pluginClass.