| 1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283 |
- //
- // SPDX-License-Identifier: BSD-3-Clause
- // Copyright (c) Contributors to the OpenEXR Project.
- //
- #ifndef INCLUDED_IEXNAMESPACE_H
- #define INCLUDED_IEXNAMESPACE_H
- //
- // The purpose of this file is to make it possible to specify an
- // IEX_INTERNAL_NAMESPACE as a preprocessor definition and have all of the
- // Iex symbols defined within that namespace rather than the standard
- // Iex namespace. Those symbols are made available to client code through
- // the IEX_NAMESPACE in addition to the IEX_INTERNAL_NAMESPACE.
- //
- // To ensure source code compatibility, the IEX_NAMESPACE defaults to Iex
- // and then "using namespace IEX_INTERNAL_NAMESPACE;" brings all of the
- // declarations from the IEX_INTERNAL_NAMESPACE into the IEX_NAMESPACE. This
- // means that client code can continue to use syntax like Iex::BaseExc, but
- // at link time it will resolve to a mangled symbol based on the
- // IEX_INTERNAL_NAMESPACE.
- //
- // As an example, if one needed to build against a newer version of Iex and
- // have it run alongside an older version in the same application, it is now
- // possible to use an internal namespace to prevent collisions between the
- // older versions of Iex symbols and the newer ones. To do this, the
- // following could be defined at build time:
- //
- // IEX_INTERNAL_NAMESPACE = Iex_v2
- //
- // This means that declarations inside Iex headers look like this (after the
- // preprocessor has done its work):
- //
- // namespace Iex_v2 {
- // ...
- // class declarations
- // ...
- // }
- //
- // namespace Iex {
- // using namespace Iex_v2;
- // }
- //
- //
- // Open Source version of this file pulls in the IexConfig.h file
- // for the configure time options.
- //
- #include "IexConfig.h"
- #ifndef IEX_NAMESPACE
- #define IEX_NAMESPACE Iex
- #endif
- #ifndef IEX_INTERNAL_NAMESPACE
- #define IEX_INTERNAL_NAMESPACE IEX_NAMESPACE
- #endif
- //
- // We need to be sure that we import the internal namespace into the public one.
- // To do this, we use the small bit of code below which initially defines
- // IEX_INTERNAL_NAMESPACE (so it can be referenced) and then defines
- // IEX_NAMESPACE and pulls the internal symbols into the public namespace.
- //
- namespace IEX_INTERNAL_NAMESPACE {}
- namespace IEX_NAMESPACE {
- using namespace IEX_INTERNAL_NAMESPACE;
- }
- //
- // There are identical pairs of HEADER/SOURCE ENTER/EXIT macros so that
- // future extension to the namespace mechanism is possible without changing
- // project source code.
- //
- #define IEX_INTERNAL_NAMESPACE_HEADER_ENTER namespace IEX_INTERNAL_NAMESPACE {
- #define IEX_INTERNAL_NAMESPACE_HEADER_EXIT }
- #define IEX_INTERNAL_NAMESPACE_SOURCE_ENTER namespace IEX_INTERNAL_NAMESPACE {
- #define IEX_INTERNAL_NAMESPACE_SOURCE_EXIT }
- #endif // INCLUDED_IEXNAMESPACE_H
|