Scripted Builder

ScriptedPicoContainer is primarily intended to be embedded inside other applications and frameworks. We recommend using a scripted container when your application consists of many loosely-coupled components that need composition driven by external scripts at runtime, ie when re-compilation is not possible.

Building a PicoContainer from a script is simple and straightforward using a ScriptedContainerBuilder. Let's look at an example: // Instantiate the reader. It should point to a script. FileReader scriptReader = new FileReader(new File("/path/to/script")); ClassLoader classLoader = Thread.currentThread().getContextClassLoader(); // Build the container from the script. GroovyContainerBuilder is used in this example // but any ScriptedContainerBuilder can be used depending on the script type being read. ScriptedContainerBuilder builder = new GroovyContainerBuilder(scriptReader, classLoader) PicoContainer parent = new DefaultPicoContainer(classLoader); Object assemblyScope = "an assembly scope"; boolean addChildToParent = true; PicoContainer container = builder.buildContainer(parent, assemblyScope, addChildToParent);

Do note that both parent container and assembly scope are optional and may be set to null. The assembly scope is simply a hint that may be used by container builders to build multiple container content. The container may or may not be added to the parent container - provided it is present.

The contract for interpreted languages is defined as follows:

1. The scripts have to define a pico variable of type MutablePicoContainer
2. The script has access to a variable named "parent", which is a MutablePicoContainer instance or null. It should be used when constructing the pico MutablePicoContainer
3. The script has access to a variable named assemblyScope that may be used in order to decide how to compose the container. The value of this variable can be any kind of object.

Let's now in more detail at the supported interpreted languages for container composition, giving a sample script for each:

• Beanshell: we can just use Java pico = new org.picocontainer.DefaultPicoContainer(parent); pico.registerComponent(org.picocontainer.script.testmodel.DefaultWebServerConfig); pico.registerComponent(org.picocontainer.script.testmodel.WebServerImpl);
• Groovy: we can use Java as in Beanshell or use the builder syntax pico = builder.container(parent:parent) { component(class:org.picocontainer.script.testmodel.DefaultWebServerConfig) component(class:org.picocontainer.script.testmodel.WebServerImpl) }
• JRuby: a similar builder syntax to Groovy DefaultWebServerConfig = org.picocontainer.script.testmodel.DefaultWebServerConfig WebServerImpl = org.picocontainer.script.testmodel.WebServerImpl container { component(:class => DefaultWebServerConfig) component(:class => WebServerImpl) }
• Jython: from org.picocontainer.script import * from org.picocontainer.script.testmodel import * pico = DefaultPicoContainer(parent); pico.registerComponent(DefaultWebServerConfig); pico.registerComponent(WebServerImpl);
• Rhino: importPackage(Packages.org.picocontainer) importPackage(Packages.org.picocontainer.script) importPackage(Packages.org.picocontainer.script.testmodel) var pico = new DefaultPicoContainer(parent) pico.registerComponent(DefaultWebServerConfig) pico.registerComponent(WebServerImpl)

The above examples in XML would be rendered as: <container> <component-implementation class='org.picocontainer.script.testmodel.DefaultWebServerConfig' /> <component-implementation class='org.picocontainer.script.testmodel.WebServerImpl' /> </container>