[pclasses-cvs] pclasses2/include/pclasses FactoryReg.h,NONE,1.1

[stephan b. <sg...@us...>]

Update of /cvsroot/pclasses/pclasses2/include/pclasses
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv24381

Added Files:
	FactoryReg.h 
Log Message:
egg

--- NEW FILE: FactoryReg.h ---
////////////////////////////////////////////////////////////////////////
// FactoryReg.h
// A "supermacro"-style classloader registration snippet for P::Factory.
////////////////////////////////////////////////////////////////////////
// Macros to be set before including this file:
//
// PFACREG_TYPE: type to be registered.
//
// PFACREG_TYPE_NAME: string name to register PFACREG_TYPE with.
//
// PFACREG_TYPE_INTERFACE: base-most type of PFACREG_TYPE.
// Defaults to PFACREG_TYPE.
//
// OPTIONAL/special-case macros:
//
// PFACREG_TYPE_IS_ABSTRACT:
// This macro should be used only when PFACREG_TYPE is an abstract type.
// If PFACREG_TYPE is an abstract base class, define this
// macro to any value. If this is set then a no-op specialization
// of P::Hook::FactoryCreateHook<> is installed so no calls to 
// new PFACREG_TYPE will be made by the default factories. 
//
//
// All of the above macros are #undef'd by this file, so it may be
// included multiple times in succession.
////////////////////////////////////////////////////////////////////////

#ifndef PFACREG_TYPE
#  error "You must define PFACREG_TYPE before including this file."
#endif

#ifndef PFACREG_TYPE_NAME
#  error "You must define PFACREG_TYPE_NAME before including this file."
#endif

#ifndef PFACREG_TYPE_INTERFACE
#  define PFACREG_TYPE_INTERFACE PFACREG_TYPE
#endif


#  ifdef PFACREG_TYPE_IS_ABSTRACT
// install a specialization of Factory's default factory type,
// so that we won't try to instantiation a PFACREG_TYPE object.
// Remember that this code will only happen when
// ( PFACREG_TYPE_INTERFACE == PFACREG_TYPE )
// assuming the user doesn't mis-use the supermacro API.
namespace P { namespace Hook {
	template <>
	struct FactoryCreateHook< PFACREG_TYPE_INTERFACE , PFACREG_TYPE >
	{
		typedef PFACREG_TYPE_INTERFACE * result_type;
		typedef PFACREG_TYPE actual_type;
		static result_type create()
		{
			return 0;
		}
	};
} } // namespace P::Hook
#  endif // PFACREG_TYPE_IS_ABSTRACT

namespace {

#  ifndef p_FACTORY_REG_CONTEXT_DEFINED
#  define p_FACTORY_REG_CONTEXT_DEFINED 1
	///////////////////////////////////////////////////////////////
	// we must not include this more than once per compilation unit
	///////////////////////////////////////////////////////////////
	// A unique (per Context/per compilation unit) space to assign
	// a bogus value for classloader registration purposes (see
	// the classloader docs for a full description of how this
	// works).
	template <typename Context>
	struct pfactory_reg_context
	{
		static bool placeholder;
	};
	template <typename Context> bool pfactory_reg_context<Context>::placeholder = false;
#  endif // !p_FACTORY_REG_CONTEXT_DEFINED

#  define FACTORY_FUNCTION_ ::P::Hook::FactoryCreateHook< PFACREG_TYPE_INTERFACE , PFACREG_TYPE >::create
	////////////////////////////////////////////////////////////////////////
	// Register a factory with the classloader:
	bool pfactory_reg_context< PFACREG_TYPE >::placeholder= (
		P::NamedTypeFactory< PFACREG_TYPE_INTERFACE >::instance().registerFactory( PFACREG_TYPE_NAME, FACTORY_FUNCTION_ ),
		true);
#  undef FACTORY_FUNCTION_
} // anon namespace

#ifdef PFACREG_TYPE_IS_ABSTRACT
#  undef PFACREG_TYPE_IS_ABSTRACT
#endif
#undef PFACREG_TYPE
#undef PFACREG_TYPE_INTERFACE
#undef PFACREG_TYPE_NAME