Function object
In Ruby, several objects can be considered function objects, in particular Method and Proc objects. Ruby also has two kinds of objects that can be thought of as semi-function objects: UnboundMethod and block. UnboundMethods must first be bound to an object (thus becoming a Method) before they can be used as a function object. Blocks can be called like function objects, but to be used in any other capacity as an object (e.g. passed as an argument) they must first be converted to a Proc. More recently, symbols (accessed via the literal unary indicator codice_35) can also be converted to codice_36s. Using Ruby's unary codice_37 operator—equivalent to calling codice_38 on an object, and assuming that method exists—the Ruby Extensions Project created a simple hack.
Common Object Request Broker Architecture
This table presents the history of CORBA standard versions.
A servant is the invocation target containing methods for handling the remote method invocations. In the newer CORBA versions, the remote object (on the server side) is split into the object "(that is exposed to remote invocations)" and servant "(to which the former part forwards the method calls)". It can be one "servant" per remote "object", or the same servant can support several (possibly all) objects, associated with the given Portable Object Adapter. The "servant" for each "object" can be set or found "once and forever" (servant activation) or dynamically chosen each time the method on that object is invoked (servant location). Both servant locator and servant activator can forward the calls to another server. In total, this system provides a very powerful means to balance the load, distributing requests between several machines. In the object-oriented languages, both remote "object" and its "servant" are objects from the viewpoint of the object-oriented programming.