2 * Copyright Andrey Semashev 2007 - 2015.
3 * Distributed under the Boost Software License, Version 1.0.
4 * (See accompanying file LICENSE_1_0.txt or copy at
5 * http://www.boost.org/LICENSE_1_0.txt)
9 * \author Andrey Semashev
12 * \brief This header is the Boost.Log library implementation, see the library documentation
13 * at http://www.boost.org/doc/libs/release/libs/log/doc/html/index.html.
16 #ifndef BOOST_LOG_DETAIL_SINGLETON_HPP_INCLUDED_
17 #define BOOST_LOG_DETAIL_SINGLETON_HPP_INCLUDED_
19 #include <boost/log/detail/config.hpp>
20 #include <boost/log/utility/once_block.hpp>
21 #include <boost/log/detail/header.hpp>
23 #ifdef BOOST_HAS_PRAGMA_ONCE
29 BOOST_LOG_OPEN_NAMESPACE
33 //! A base class for singletons, constructed on-demand
34 template< typename DerivedT, typename StorageT = DerivedT >
38 BOOST_DEFAULTED_FUNCTION(lazy_singleton(), {})
40 //! Returns the singleton instance
41 static StorageT& get()
43 BOOST_LOG_ONCE_BLOCK()
45 DerivedT::init_instance();
47 return get_instance();
50 //! Initializes the singleton instance
51 static void init_instance()
56 BOOST_DELETED_FUNCTION(lazy_singleton(lazy_singleton const&))
57 BOOST_DELETED_FUNCTION(lazy_singleton& operator= (lazy_singleton const&))
60 //! Returns the singleton instance (not thread-safe)
61 static StorageT& get_instance()
63 static StorageT instance;
68 //! A base class for singletons, constructed on namespace scope initialization stage
69 template< typename DerivedT, typename StorageT = DerivedT >
71 public lazy_singleton< DerivedT, StorageT >
74 static StorageT& instance;
77 template< typename DerivedT, typename StorageT >
78 StorageT& singleton< DerivedT, StorageT >::instance =
79 lazy_singleton< DerivedT, StorageT >::get();
83 BOOST_LOG_CLOSE_NAMESPACE // namespace log
87 #include <boost/log/detail/footer.hpp>
89 #endif // BOOST_LOG_DETAIL_SINGLETON_HPP_INCLUDED_