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/*******************************************************************************
* Copyright (c) 2000, 2006 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.core.runtime;
/**
* An extension declared in a plug-in.
* All information is obtained from the declaring plug-in's
* manifest (<code>plugin.xml</code>) file.
* <p>
* These registry objects are intended for relatively short-term use. Clients that
* deal with these objects must be aware that they may become invalid if the
* declaring plug-in is updated or uninstalled. If this happens, all methods except
* {@link #isValid()} will throw {@link InvalidRegistryObjectException}.
* For extension objects, the most common case is code in a plug-in dealing
* with extensions contributed to one of the extension points it declares.
* Code in a plug-in that has declared that it is not dynamic aware (or not
* declared anything) can safely ignore this issue, since the registry
* would not be modified while it is active. However, code in a plug-in that
* declares that it is dynamic aware must be careful when accessing the extension
* objects because they become invalid if the contributing plug-in is removed.
* Similarly, tools that analyze or display the extension registry are vulnerable.
* Client code can pre-test for invalid objects by calling {@link #isValid()},
* which never throws this exception. However, pre-tests are usually not sufficient
* because of the possibility of the extension object becoming invalid as a
* result of a concurrent activity. At-risk clients must treat
* <code>InvalidRegistryObjectException</code> as if it were a checked exception.
* Also, such clients should probably register a listener with the extension registry
* so that they receive notification of any changes to the registry.
* </p>
* <p>
* This interface is not intended to be implemented by clients.
* </p>
*/
public interface IExtension {
/**
* Returns all configuration elements declared by this extension.
* These elements are a direct reflection of the configuration
* markup supplied in the manifest (<code>plugin.xml</code>)
* file for the plug-in that declares this extension.
* Returns an empty array if this extension does not declare any
* configuration elements.
*
* @return the configuration elements declared by this extension
* @throws InvalidRegistryObjectException if this extension is no longer valid
*/
public IConfigurationElement[] getConfigurationElements() throws InvalidRegistryObjectException;
/**
* Returns the namespace for this extension. This value can be used
* in various global facilities to discover this extension's provider.
*
* @return the namespace for this extension
* @throws InvalidRegistryObjectException if this extension is no longer valid
* @see IExtensionRegistry
* @since 3.0
*/
public String getNamespace() throws InvalidRegistryObjectException;
/**
* Returns the unique identifier of the extension point
* to which this extension should be contributed.
*
* @return the unique identifier of the relevant extension point
* @throws InvalidRegistryObjectException if this extension is no longer valid
*/
public String getExtensionPointUniqueIdentifier() throws InvalidRegistryObjectException;
/**
* Returns a displayable label for this extension.
* Returns the empty string if no label for this extension
* is specified in the plug-in manifest file.
* <p> Note that any translation specified in the plug-in manifest
* file is automatically applied.
* <p>
*
* @return a displayable string label for this extension,
* possibly the empty string
* @throws InvalidRegistryObjectException if this extension is no longer valid
*/
public String getLabel() throws InvalidRegistryObjectException;
/**
* Returns the simple identifier of this extension, or <code>null</code>
* if this extension does not have an identifier.
* This identifier is specified in the plug-in manifest (<code>plugin.xml</code>)
* file as a non-empty string containing no period characters
* (<code>'.'</code>) and must be unique within the defining plug-in.
*
* @return the simple identifier of the extension (e.g. <code>"main"</code>)
* or <code>null</code>
* @throws InvalidRegistryObjectException if this extension is no longer valid
*/
public String getSimpleIdentifier() throws InvalidRegistryObjectException;
/**
* Returns the unique identifier of this extension, or <code>null</code>
* if this extension does not have an identifier.
* If available, this identifier is unique within the plug-in registry, and
* is composed of the namespace where this extension
* was declared and this extension's simple identifier.
*
* @return the unique identifier of the extension
* (e.g. <code>"com.example.acme.main"</code>), or <code>null</code>
* @throws InvalidRegistryObjectException if this extension is no longer valid
*/
public String getUniqueIdentifier() throws InvalidRegistryObjectException;
/* (non-javadoc)
* @see Object#equals(java.lang.Object)
*/
public boolean equals(Object o);
/**
* Returns whether this extension object is valid.
*
* @return <code>true</code> if the object is valid, and <code>false</code>
* if it is no longer valid
* @since 3.1
*/
public boolean isValid();
}
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