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//
// InstanceExtensionNode.cs
//
// Author:
// Lluis Sanchez Gual
//
// Copyright (C) 2007 Novell, Inc (http://www.novell.com)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
namespace Mono.Addins
{
/// <summary>
/// Base class for extension nodes which create extension objects
/// </summary>
public abstract class InstanceExtensionNode: ExtensionNode
{
object cachedInstance;
/// <summary>
/// Gets the extension object declared by this node
/// </summary>
/// <param name="expectedType">
/// Expected object type. An exception will be thrown if the object is not an instance of the specified type.
/// </param>
/// <returns>
/// The extension object
/// </returns>
/// <remarks>
/// The extension object is cached and the same instance will be returned at every call.
/// </remarks>
public object GetInstance (Type expectedType)
{
object ob = GetInstance ();
if (!expectedType.IsInstanceOfType (ob))
throw new InvalidOperationException (string.Format ("Expected subclass of type '{0}'. Found '{1}'.", expectedType, ob.GetType ()));
return ob;
}
/// <summary>
/// Gets the extension object declared by this node
/// </summary>
/// <returns>
/// The extension object
/// </returns>
/// <remarks>
/// The extension object is cached and the same instance will be returned at every call.
/// </remarks>
public object GetInstance ()
{
if (cachedInstance == null)
cachedInstance = CreateInstance ();
return cachedInstance;
}
/// <summary>
/// Creates a new extension object
/// </summary>
/// <param name="expectedType">
/// Expected object type. An exception will be thrown if the object is not an instance of the specified type.
/// </param>
/// <returns>
/// The extension object
/// </returns>
public object CreateInstance (Type expectedType)
{
object ob = CreateInstance ();
if (!expectedType.IsInstanceOfType (ob))
throw new InvalidOperationException (string.Format ("Expected subclass of type '{0}'. Found '{1}'.", expectedType, ob.GetType ()));
return ob;
}
/// <summary>
/// Creates a new extension object
/// </summary>
/// <returns>
/// The extension object
/// </returns>
public abstract object CreateInstance ();
}
}
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