Extension support

Extensions provide a possibility to extend certain aspects of a solution or a language, which are not covered by the standard language aspects and the plugin mechanisms. Typically, you may need your language to slightly alter its behavior depending on the distribution model, such as an MPS plugin or a standalone IDE. In such cases you define your extension points as interfaces to which then different implementations will be provided in different distributions.

Support for extensions exists in

languages
plugin solutions

Quick howto

Create an extension point
- An extension point must be defined in a plugin aspect of a language or in a plugin solution.
- A plugin solution must have the Contributes extensions to MPS option set to yes on theJava tab of the solution properties dialog.
Create one or more extensions
- Extensions must be defined in the plugin aspect of a language or in a plugin solution.
- A plugin solution must have the Contributes extensions to MPS option set to yes on theJava tab of the solution properties dialog.
- Each extension must provide a get method, returning an object
- Each extension may opt in to receive the activate/deactivate notifications
- An extension may declare fields, just like classes can

Extension language

The language jetbrains.mps.lang.extension declares concepts necessary for building extensions.

Extension point

The ExtensionPointDeclaration concept represents an extension point. The extension object type must be specified as a parameter.

Extension

The Extension concept is used to create a concrete extension.

Accessing extension point

An extension point can be accessed by reference using extension point expression.

Accessing extension objects

An extension point includes a way to access all objects provided by its extensions.

Java API

   public interface Extension<T> {

       String getExtensionPointId ();

       T get ();

       void activate ();

       void deactivate ();
   }

   public class ExtensionPoint<T> {

       public static <T> ExtensionPoint<T> generify(ExtensionPoint raw) { ... }

       public ExtensionPoint(String id) { ... }

       public String getId() { ... }
   }

Extension points and extensions are managed by the ExtensionRegistry core component.

07 July 2025