1 // 2 // InstanceExtensionNode.cs 3 // 4 // Author: 5 // Lluis Sanchez Gual 6 // 7 // Copyright (C) 2007 Novell, Inc (http://www.novell.com) 8 // 9 // Permission is hereby granted, free of charge, to any person obtaining 10 // a copy of this software and associated documentation files (the 11 // "Software"), to deal in the Software without restriction, including 12 // without limitation the rights to use, copy, modify, merge, publish, 13 // distribute, sublicense, and/or sell copies of the Software, and to 14 // permit persons to whom the Software is furnished to do so, subject to 15 // the following conditions: 16 // 17 // The above copyright notice and this permission notice shall be 18 // included in all copies or substantial portions of the Software. 19 // 20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 27 // 28 29 30 using System; 31 32 namespace Mono.Addins 33 { 34 /// <summary> 35 /// Base class for extension nodes which create extension objects 36 /// </summary> 37 public abstract class InstanceExtensionNode: ExtensionNode 38 { 39 object cachedInstance; 40 41 /// <summary> 42 /// Gets the extension object declared by this node 43 /// </summary> 44 /// <param name="expectedType"> 45 /// Expected object type. An exception will be thrown if the object is not an instance of the specified type. 46 /// </param> 47 /// <returns> 48 /// The extension object 49 /// </returns> 50 /// <remarks> 51 /// The extension object is cached and the same instance will be returned at every call. 52 /// </remarks> GetInstance(Type expectedType)53 public object GetInstance (Type expectedType) 54 { 55 object ob = GetInstance (); 56 if (!expectedType.IsInstanceOfType (ob)) 57 throw new InvalidOperationException (string.Format ("Expected subclass of type '{0}'. Found '{1}'.", expectedType, ob.GetType ())); 58 return ob; 59 } 60 61 /// <summary> 62 /// Gets the extension object declared by this node 63 /// </summary> 64 /// <returns> 65 /// The extension object 66 /// </returns> 67 /// <remarks> 68 /// The extension object is cached and the same instance will be returned at every call. 69 /// </remarks> GetInstance()70 public object GetInstance () 71 { 72 if (cachedInstance == null) 73 cachedInstance = CreateInstance (); 74 return cachedInstance; 75 } 76 77 /// <summary> 78 /// Creates a new extension object 79 /// </summary> 80 /// <param name="expectedType"> 81 /// Expected object type. An exception will be thrown if the object is not an instance of the specified type. 82 /// </param> 83 /// <returns> 84 /// The extension object 85 /// </returns> CreateInstance(Type expectedType)86 public object CreateInstance (Type expectedType) 87 { 88 object ob = CreateInstance (); 89 if (!expectedType.IsInstanceOfType (ob)) 90 throw new InvalidOperationException (string.Format ("Expected subclass of type '{0}'. Found '{1}'.", expectedType, ob.GetType ())); 91 return ob; 92 } 93 94 /// <summary> 95 /// Creates a new extension object 96 /// </summary> 97 /// <returns> 98 /// The extension object 99 /// </returns> CreateInstance()100 public abstract object CreateInstance (); 101 } 102 } 103