-qobjmodel (C++ only)

Pragma equivalent

#pragma object_model

Purpose

Sets the object model to be used for structures, unions, and classes.

The object models differ in the following areas:

Layout for the virtual function table
Virtual base class support
Name mangling scheme

Syntax


Option syntax

                     .-classic-.   
>>- -q--objmodel--=--+-ibm-----+-------------------------------><


Pragma syntax

                             .-classic-.   
>>-#pragma--object_model--(--+-ibm-----+-----------------------><
                             +-pop-----+   
                             '-)-------'

Defaults

-qobjmodel=classic

Parameters

classic: Uses the object model compatible with V3.6 of the IBM® C++ Compiler. This suboption can also be specified using the legacy suboption name of -qobjmodel=compat, but support for this legacy suboption name may be removed in future releases of the compiler.
ibm: Uses the object model introduced with VisualAge® C++ V5.0. Objects compiled with this object model will use less memory and have better performance for deep inheritance with virtual bases.
pop (pragma only): Discards the current pragma setting and reverts to the setting specified by the previous pragma directive. If no previous pragma was specified, reverts to the command-line or default option setting.

Usage

All classes in the same inheritance hierarchy must have the same object model.

Predefined macros

__OBJECT_MODEL_CLASSIC__ is predefined to 1 when -qobjmodel=classic or #pragma object_model(classic) is in effect (the default); otherwise, it is undefined.
__OBJECT_MODEL_IBM__ is predefined to 1 when -qobjmodel=ibm or #pragma object_model(ibm) is in effect; otherwise, it is undefined.

Examples

To compile myprogram.C with the ibm object model, enter:

xlc++ myprogram.C -qobjmodel=ibm