## Class template basic_logger

boost::log::sources::basic_logger — Basic logger class.

## Synopsis

    // In header: <boost/log/sources/basic_logger.hpp>

    template<typename CharT, typename FinalT, typename ThreadingModelT>
    class basic_logger : public ThreadingModelT {
    public:
      // types
      typedef CharT                      char_type;                   // Character type.
      typedef FinalT                     final_type;                  // Final logger type.
      typedef ThreadingModelT            threading_model;             // Threading model type.
      typedef unspecified                swap_lock;                   // Lock requirement for the swap_unlocked method.
      typedef unspecified                add_attribute_lock;          // Lock requirement for the add_attribute_unlocked method.
      typedef unspecified                remove_attribute_lock;       // Lock requirement for the remove_attribute_unlocked method.
      typedef unspecified                remove_all_attributes_lock;  // Lock requirement for the remove_all_attributes_unlocked method.
      typedef unspecified                get_attributes_lock;         // Lock requirement for the get_attributes method.
      typedef unspecified                open_record_lock;            // Lock requirement for the open_record_unlocked method.
      typedef unspecified                set_attributes_lock;         // Lock requirement for the set_attributes method.
      typedef no_lock< threading_model > push_record_lock;            // Lock requirement for the push_record_unlocked method.

      // construct/copy/destruct
      basic_logger();
      basic_logger(basic_logger const &);
      basic_logger(basic_logger &&);
      template<typename ArgsT> explicit basic_logger(ArgsT const &);
      basic_logger & operator=(basic_logger const &) = delete;

      // protected member functions
      core_ptr const & core() const;
      attribute_set & attributes();
      attribute_set const & attributes() const;
      threading_model & get_threading_model();
      threading_model const & get_threading_model() const;
      final_type * final_this();
      final_type const * final_this() const;
      void swap_unlocked(basic_logger &);
      std::pair< attribute_set::iterator, bool >
      add_attribute_unlocked(attribute_name const &, attribute const &);
      void remove_attribute_unlocked(attribute_set::iterator);
      void remove_all_attributes_unlocked();
      record open_record_unlocked();
      template<typename ArgsT> record open_record_unlocked(ArgsT const &);
      void push_record_unlocked(record &&);
      attribute_set get_attributes_unlocked() const;
      void set_attributes_unlocked(attribute_set const &);
    };

## Description

The `basic_logger` class template serves as a base class for all loggers provided by the library. It can also be used as a base for user-defined loggers. The template parameters are:

- `CharT` - logging character type

- `FinalT` - final type of the logger that eventually derives from the `basic_logger`. There may be other classes in the hierarchy between the final class and `basic_logger`.

- `ThreadingModelT` - threading model policy. Must provide methods of the Boost.Thread locking concept used in `basic_logger` class and all its derivatives in the hierarchy up to the `FinalT` class. The `basic_logger` class itself requires methods of the SharedLockable concept. The threading model policy must also be default and copy-constructible and support member function `swap`. There are currently two policies provided: `single_thread_model` and `multi_thread_model`.

The logger implements fundamental facilities of loggers, such as storing source-specific attribute set and formatting log record messages. The basic logger interacts with the logging core in order to apply filtering and pass records to sinks.

### `basic_logger` public construct/copy/destruct

1.     basic_logger();

   Constructor. Initializes internal data structures of the basic logger class, acquires reference to the logging core.

2.     basic_logger(basic_logger const & that);

   Copy constructor. Copies all attributes from the source logger.

   | Note
   Not thread-safe. The source logger must be locked in the final class before copying.

   Parameters:

   `that` | Source logger

3.     basic_logger(basic_logger && that);

   Move constructor. Moves all attributes from the source logger.

   | Note
   Not thread-safe. The source logger must be locked in the final class before copying.

   Parameters:

   `that` | Source logger

4.     template<typename ArgsT> explicit basic_logger(ArgsT const &);

   Constructor with named arguments. The constructor ignores all arguments. The result of construction is equivalent to default construction.

5.     basic_logger & operator=(basic_logger const &) = delete;

   Assignment is closed (should be implemented through copy and swap in the final class)

### `basic_logger` protected member functions

1.     core_ptr const & core() const;

   An accessor to the logging system pointer

2.     attribute_set & attributes();

   An accessor to the logger attributes

3.     attribute_set const & attributes() const;

   An accessor to the logger attributes

4.     threading_model & get_threading_model();

   An accessor to the threading model base

5.     threading_model const & get_threading_model() const;

   An accessor to the threading model base

6.     final_type * final_this();

   An accessor to the final logger

7.     final_type const * final_this() const;

   An accessor to the final logger

8.     void swap_unlocked(basic_logger & that);

   Unlocked `swap`

9.     std::pair< attribute_set::iterator, bool >
       add_attribute_unlocked(attribute_name const & name, attribute const & attr);

   Unlocked `add_attribute`

10.     void remove_attribute_unlocked(attribute_set::iterator it);

    Unlocked `remove_attribute`

11.     void remove_all_attributes_unlocked();

    Unlocked `remove_all_attributes`

12.     record open_record_unlocked();

    Unlocked `open_record`

13.     template<typename ArgsT> record open_record_unlocked(ArgsT const &);

    Unlocked `open_record`

14.     void push_record_unlocked(record && rec);

    Unlocked `push_record`

15.     attribute_set get_attributes_unlocked() const;

    Unlocked `get_attributes`

16.     void set_attributes_unlocked(attribute_set const & attrs);

    Unlocked `set_attributes`