GLib.log_set_handler
Description: Reference for GLib.log_set_handler

### Function

# GLiblog_set_handler

since: 2.0

#### Declaration

    guint
    g_log_set_handler (
      const gchar* log_domain,
      GLogLevelFlags log_levels,
      GLogFunc log_func,
      gpointer user_data
    )

#### Description

Sets the log handler for a domain and a set of log levels.

To handle fatal and recursive messages the `log_levels` parameter must be combined with the `GLogLevelFlags` and `GLogLevelFlags` bit flags.

Note that since the `GLogLevelFlags` log level is always fatal, if you want to set a handler for this log level you must combine it with `GLogLevelFlags`.

This has no effect if structured logging is enabled; see Using Structured Logging.

Here is an example for adding a log handler for all warning messages in the default domain:

    g_log_set_handler (NULL, G_LOG_LEVEL_WARNING | G_LOG_FLAG_FATAL
                       | G_LOG_FLAG_RECURSION, my_log_handler, NULL);

This example adds a log handler for all critical messages from GTK:

    g_log_set_handler ("Gtk", G_LOG_LEVEL_CRITICAL | G_LOG_FLAG_FATAL
                       | G_LOG_FLAG_RECURSION, my_log_handler, NULL);

This example adds a log handler for all messages from GLib:

    g_log_set_handler ("GLib", G_LOG_LEVEL_MASK | G_LOG_FLAG_FATAL
                       | G_LOG_FLAG_RECURSION, my_log_handler, NULL);

Available since: 2.0

This function is not directly available to language bindings.

The implementation of this method is provided by `g_log_set_handler_full()` in language bindings

#### Parameters

`log_domain`

  Type: `const gchar*`

  The log domain, or `NULL` for the default `""` application domain.

  The argument can be `NULL`.
  The data is owned by the caller of the function.
  The value is a NUL terminated UTF-8 string.

`log_levels`

  Type: `GLogLevelFlags`

  The log levels to apply the log handler for. To handle fatal and recursive messages as well, combine the log levels with the `GLogLevelFlags` and `GLogLevelFlags` bit flags.

`log_func`

  Type: `GLogFunc`

  The log handler function.

`user_data`

  Type: `gpointer`

  Data passed to the log handler.

  The argument can be `NULL`.
  The data is owned by the caller of the function.

#### Return value

Type: `guint`

The id of the new handler.