Type IDs
Slice interfaces, classes, and user exceptions have an internal type identifier, known as the type ID. The type ID is simply the fully-qualified Slice name of each construct. For example, the type ID of the Child interface in the preceding example is ::Family::Child. A type ID starts with a leading :: and is formed by starting with the global scope (::) and forming the fully-qualified name of a construct by appending each module name in which the construct is nested, and ending with the name of the construct itself; the components of the type ID are separated by ::.
The term “type ID” is a historical accident: of the 3 constructs with type IDs, only classes are types in the Slice language. Neither interfaces nor exceptions are types in Slice.
Type IDs are used internally by Ice to unmarshal classes and exceptions. For example, when an exception is thrown, the marshaled form of the exception that is returned to the client is preceded by its type ID on the wire. The client-side runtime first reads the type ID and, based on that, unmarshals the remainder of the data as appropriate for the type of the exception.
Type IDs are also used by the ice_isA operation.