Eclipse Plug-in Developer Guide (Galileo) - IExtensionPoint (Eclipse Platform API Specification)

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Eclipse Platform
Release 3.5

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org.eclipse.core.runtime
Interface IExtensionPoint

public interface IExtensionPoint

An extension point declared in a plug-in. Except for the list of extensions plugged in to it, the information available for an extension point is obtained from the declaring plug-in's manifest (plugin.xml) file.

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 isValid() will throw InvalidRegistryObjectException. For extension point objects, the most common case is code in a plug-in dealing with one of the extension points it declares. These extension point objects are guaranteed to be valid while the plug-in is active. Code in a plug-in that has declared that it is not dynamic aware (or not declared anything) can also 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 if it access the extension point object of a different plug-in, because it's at risk if that other 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 isValid(), which never throws this exception. However, pre-tests are usually not sufficient because of the possibility of the extension point object becoming invalid as a result of a concurrent activity. At-risk clients must treat InvalidRegistryObjectException 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.

This interface can be used without OSGi running.

This interface is not intended to be implemented by clients.

Restriction:: This interface is not intended to be implemented by clients.

Method Summary

boolean equals ( Object o)


IConfigurationElement[] getConfigurationElements ()
          Returns all configuration elements from all extensions configured into this extension point.

IContributor getContributor ()
          Returns the contributor of this extension point.

IExtension getExtension ( String extensionId)
          Returns the extension with the given unique identifier configured into this extension point, or null if there is no such extension.

IExtension[] getExtensions ()
          Returns all extensions configured into this extension point.

String getLabel ()
          Returns a displayable label for this extension point.

String getNamespace ()
          Deprecated. As namespace is no longer restricted to the contributor name, use getNamespaceIdentifier() to obtain namespace name or getContributor() to get the name of the contributor of this registry element.
In the past namespace was dictated by the name of the bundle. If bundle org.abc contributed registry element with Id of MyId, the namespace of the element was always set to org.abc, producing the qualified name of org.abc.MyId.

The namespace used to be the same as the bundle name. As a result, the getNamespace() method was used both to obtain the name of the bundle and to obtain the namespace of a registry element.

Since 3.2, the extension registry allows elements to specify qualified name. The extension point of the plug-in org.abc could specify org.zzz.MyExtPoint as an Id. In this case, namespace name is org.zzz, but the contributor name is org.abc.

(The use of a simple Id is still a preferred way. Whenever possible, specify only the simple Id and let runtime take care of the rest.)

If your code used the getNamespace() to obtain the name of the contributing bundle, use getContributor(). The typical usage pattern here is to find a bundle name to obtain some information from the corresponding OSGi bundle. For example, deducing the file location specified as a relative path to the bundle install location would fall into this group.

If your code used the getNamespace() to obtain the namespace of the registry element, use getNamespaceIdentifier(). Typically, this is the case when code is trying to process registry elements belonging to some logical group. For example, processing notifications for all elements belonging to the org.abc namespace would fall into this category.

String getNamespaceIdentifier ()
          Returns the namespace name for this extension point.

String getSchemaReference ()
          Returns reference to the extension point schema.

String getSimpleIdentifier ()
          Returns the simple identifier of this extension point.

String getUniqueIdentifier ()
          Returns the unique identifier of this extension point.

boolean isValid ()
          Returns whether this extension point object is valid.

Method Detail

getConfigurationElements


IConfigurationElement[] getConfigurationElements()
                                                 throws 
InvalidRegistryObjectException

Returns all configuration elements from all extensions configured into this extension point. Returns an empty array if this extension point has no extensions configured, or none of the extensions contain configuration elements.

Returns:: the configuration elements for all extension configured into this extension point
Throws:: InvalidRegistryObjectException - if this extension point is no longer valid

getNamespace


String getNamespace()
                    throws 
InvalidRegistryObjectException

Deprecated. As namespace is no longer restricted to the contributor name, use getNamespaceIdentifier() to obtain namespace name or getContributor() to get the name of the contributor of this registry element.
In the past namespace was dictated by the name of the bundle. If bundle org.abc contributed registry element with Id of MyId, the namespace of the element was always set to org.abc, producing the qualified name of org.abc.MyId.

The namespace used to be the same as the bundle name. As a result, the getNamespace() method was used both to obtain the name of the bundle and to obtain the namespace of a registry element.

Since 3.2, the extension registry allows elements to specify qualified name. The extension point of the plug-in org.abc could specify org.zzz.MyExtPoint as an Id. In this case, namespace name is org.zzz, but the contributor name is org.abc.

(The use of a simple Id is still a preferred way. Whenever possible, specify only the simple Id and let runtime take care of the rest.)

If your code used the getNamespace() to obtain the name of the contributing bundle, use getContributor(). The typical usage pattern here is to find a bundle name to obtain some information from the corresponding OSGi bundle. For example, deducing the file location specified as a relative path to the bundle install location would fall into this group.

If your code used the getNamespace() to obtain the namespace of the registry element, use getNamespaceIdentifier(). Typically, this is the case when code is trying to process registry elements belonging to some logical group. For example, processing notifications for all elements belonging to the org.abc namespace would fall into this category.

Returns the namespace for this extension point. This value can be used in various global facilities to discover this extension point's provider.

Returns:: the namespace for this extension point
Throws:: InvalidRegistryObjectException - if this extension point is no longer valid
Since:: 3.0
See Also:: IExtensionRegistry

getNamespaceIdentifier


String getNamespaceIdentifier()
                              throws 
InvalidRegistryObjectException

Returns the namespace name for this extension point.

Returns:: the namespace name for this extension point
Throws:: InvalidRegistryObjectException - if this extension point is no longer valid
Since:: org.eclipse.equinox.registry 3.2

getContributor


IContributor getContributor()
                            throws 
InvalidRegistryObjectException

Returns the contributor of this extension point.

Returns:: the contributor for this extension point
Throws:: InvalidRegistryObjectException - if this extension point is no longer valid
Since:: org.eclipse.equinox.registry 3.2

getExtension


IExtension getExtension(
String extensionId)
                        throws 
InvalidRegistryObjectException

Returns the extension with the given unique identifier configured into this extension point, or null if there is no such extension. Since an extension might not have an identifier, some extensions can only be found via the getExtensions method.

Parameters:: extensionId - the unique identifier of an extension (e.g. "com.example.acme.main").
Returns:: an extension, or null
Throws:: InvalidRegistryObjectException - if this extension point is no longer valid

getExtensions


IExtension[] getExtensions()
                           throws 
InvalidRegistryObjectException

Returns all extensions configured into this extension point. Returns an empty array if this extension point has no extensions.

Returns:: the extensions configured into this extension point
Throws:: InvalidRegistryObjectException - if this extension point is no longer valid

getLabel


String getLabel()
                throws 
InvalidRegistryObjectException

Returns a displayable label for this extension point. Returns the empty string if no label for this extension point is specified in the plug-in manifest file.

Note that any translation specified in the plug-in manifest file is automatically applied.

Returns:: a displayable string label for this extension point, possibly the empty string
Throws:: InvalidRegistryObjectException - if this extension point is no longer valid

getSchemaReference


String getSchemaReference()
                          throws 
InvalidRegistryObjectException

Returns reference to the extension point schema. The schema reference is returned as a URL path relative to the plug-in installation URL. Returns the empty string if no schema for this extension point is specified in the plug-in manifest file.

Returns:: a relative URL path, or an empty string
Throws:: InvalidRegistryObjectException - if this extension point is no longer valid

getSimpleIdentifier


String getSimpleIdentifier()
                           throws 
InvalidRegistryObjectException

Returns the simple identifier of this extension point. This identifier is a non-empty string containing no period characters ('.') and is guaranteed to be unique within the namespace.

Returns:: the simple identifier of the extension point (e.g. "builders")
Throws:: InvalidRegistryObjectException - if this extension point is no longer valid

getUniqueIdentifier


String getUniqueIdentifier()
                           throws 
InvalidRegistryObjectException

Returns the unique identifier of this extension point. This identifier is unique within the plug-in registry, and is composed of the namespace for this extension point and this extension point's simple identifier.

Returns:: the unique identifier of the extension point (e.g. "org.eclipse.core.resources.builders")
Throws:: InvalidRegistryObjectException - if this extension point is no longer valid

equals

boolean equals(
Object o)

Overrides:: equals in class Object

isValid

boolean isValid()

Returns whether this extension point object is valid.

Returns:: true if the object is valid, and false if it is no longer valid
Since:: 3.1