Abstract: Providing a user interface for editing a domain specific language expression includes displaying, by a master widget, the domain specific language expression within the user interface. This displaying of the domain specific language expression includes displaying, by a compound expression widget, a compound expression of the domain specific language expression and displaying the compound expression includes displaying, by a first expression widget, a first argument of the compound expression, and displaying, by a second expression widget, a second argument of the compound expression. The method further includes detecting, by the compound expression widget, a change to either of the first expression widget and the second expression widget; and in response to the change being detected, updating, by the master widget, the compound expression based on the change.

Abstract: A technique is described that allows a software client to create at run-time a software object that appears to extend or alter the functionality of an existing software class definition. For example, a decorator factory generates a proxy object that dynamically implements a set of interfaces specified by the software client at runtime. From the perspective of the client, the proxy object is logically a child object of the original existing base object. The child object appears to be enhanced by the methods and attributes defined by the set of interfaces and the methods implemented by the delegate object. However, the proxy object does not have actual parent classes. Instead, an invocation transparently intercepts method invocations from the client to the proxy object and invokes the appropriate method, regardless of whether the method is implemented in the base object, the delegate object, or within the proxy object itself.