A.5 Mapping pseudo-objects to Lisp

Pseudo-objects are constructs whose definition is usually specified in IDL, but whose mapping is language specified. A pseudo-object is not (usually) a regular CORBA object.

A pseudo-object differs from a regular CORBA object in the following ways:

• It is not represented in the Interface Repository.
• It may not be passed as a parameter to an operation expecting a CORBA object.
• It may not be returned as a CORBA Object.
• It may not be stored in an any.
• If it is represented as a class, it may not be safely subclassed by user code.

We have chosen the option allowed in the IDL specification to define status as void and have eliminated it for the convenience of Lisp programmers.

Each of the standard IDL pseudo-objects is mapped according to the translation rules just defined.

A.5.1 Narrowing

In line with the other language binding, we define an operation for narrowing an object reference. The code:

(op:narrow class-symbol object-refence)

attempts to narrow the given object reference into an object of the named client-side class.

For example, to narrow an client-side value stored in account-ref, into an object of type Bankingdemo:Checkingaccount:

(when (op:Is_a account-ref 
        (op:id Bankingdemo:_Tc_Checkingaccount))
   (setf account-ref 
   (op:narrow 'Bankingdemo:Checkingaccount account-ref)))

A.5.2 Typecodes for parsed IDL

Parameters holding the typecode value are generated for all parsed IDL types. If the IDL parser generates a Lisp type of name A:B, then the typecode of the given type is available in the parameter A:_TC_B.

For example, the IDL code:

module example { interface array_interface{}}; 

leads to the definition of a parameter:

example:_tc_array_interface 

with:

(op:kind example:_tc_array_interface)
> :tk_objref