// Copyright 2006 The Apache Software Foundation | |
// | |
// Licensed under the Apache License, Version 2.0 (the "License"); | |
// you may not use this file except in compliance with the License. | |
// You may obtain a copy of the License at | |
// | |
// http://www.apache.org/licenses/LICENSE-2.0 | |
// | |
// Unless required by applicable law or agreed to in writing, software | |
// distributed under the License is distributed on an "AS IS" BASIS, | |
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
// See the License for the specific language governing permissions and | |
// limitations under the License. | |
package org.apache.tapestry5.ioc.services; | |
import java.util.List; | |
/** | |
* A service which can assemble an implementation based on a command interface, and an ordered list of objects | |
* implementing that interface (the "commands"). This is an implementation of the Gang of Four Chain Of Command | |
* pattern. | |
* <p/> | |
* For each method in the interface, the chain implementation will call the corresponding method on each command object | |
* in turn (with the order defined by the list). If any of the command objects return true, then the chain of command | |
* stops and the initial method invocation returns true. Otherwise, the chain of command continues to the next command | |
* (and will return false if none of the commands returns true). | |
* <p/> | |
* For methods whose return type is not boolean, the chain stops with the first non-null (for object types), or non-zero | |
* (for numeric types). The chain returns the value that was returned by the command. If the method return type is void, | |
* all commands will be invoked. | |
* <p/> | |
* Method invocations will also be terminated if an exception is thrown. | |
*/ | |
public interface ChainBuilder | |
{ | |
/** | |
* Creates a chain instance from a command interface and a list of commands (implementing the interface). | |
*/ | |
<T> T build(Class<T> commandInterface, List<T> commands); | |
} |