// Generated by gmmproc 2.88.0 -- DO NOT MODIFY!
#ifndef _GIOMM_SETTINGS_H
#define _GIOMM_SETTINGS_H

#include <giommconfig.h>


#include <glibmm/ustring.h>
#include <sigc++/sigc++.h>

/* Copyright (C) 2010 Jonathon Jongsma
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */


#include <glibmm/object.h>
#include <glibmm/variant.h>
#include <giomm/action.h>
#include <optional>


#ifndef DOXYGEN_SHOULD_SKIP_THIS
using GSettings = struct _GSettings;
using GSettingsClass = struct _GSettingsClass;
#endif /* DOXYGEN_SHOULD_SKIP_THIS */


#ifndef DOXYGEN_SHOULD_SKIP_THIS
namespace Gio
{ class GIOMM_API Settings_Class; } // namespace Gio
#endif //DOXYGEN_SHOULD_SKIP_THIS

namespace Gio
{
class GIOMM_API SettingsSchema;

/** A high-level API for application settings
 *
 * The Settings class provides a convenient API for storing and retrieving
 * application settings.
 *
 * @newin{2,28}
 */

class GIOMM_API Settings : public Glib::Object
{
  
#ifndef DOXYGEN_SHOULD_SKIP_THIS

public:
  using CppObjectType = Settings;
  using CppClassType = Settings_Class;
  using BaseObjectType = GSettings;
  using BaseClassType = GSettingsClass;

  // noncopyable
  Settings(const Settings&) = delete;
  Settings& operator=(const Settings&) = delete;

private:  friend class Settings_Class;
  static CppClassType settings_class_;

protected:
  explicit Settings(const Glib::ConstructParams& construct_params);
  explicit Settings(GSettings* castitem);

#endif /* DOXYGEN_SHOULD_SKIP_THIS */

public:

  Settings(Settings&& src) noexcept;
  Settings& operator=(Settings&& src) noexcept;

  ~Settings() noexcept override;

  /** Get the GType for this class, for use with the underlying GObject type system.
   */
  static GType get_type()      G_GNUC_CONST;

#ifndef DOXYGEN_SHOULD_SKIP_THIS


  static GType get_base_type() G_GNUC_CONST;
#endif

  ///Provides access to the underlying C GObject.
  GSettings*       gobj()       { return reinterpret_cast<GSettings*>(gobject_); }

  ///Provides access to the underlying C GObject.
  const GSettings* gobj() const { return reinterpret_cast<GSettings*>(gobject_); }

  ///Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs.
  GSettings* gobj_copy();

private:


public:
  /** @addtogroup giommEnums giomm Enums and Flags */

  /** 
   *  @var BindFlags::DEFAULT
   * Equivalent to `G_SETTINGS_BIND_GET|G_SETTINGS_BIND_SET`.
   * 
   *  @var BindFlags::GET
   * Update the GObject::Object property when the setting changes.
   * It is an error to use this flag if the property is not writable.
   * 
   *  @var BindFlags::SET
   * Update the setting when the GObject::Object property changes.
   * It is an error to use this flag if the property is not readable.
   * 
   *  @var BindFlags::NO_SENSITIVITY
   * Do not try to bind a ‘sensitivity’ property to the writability of the setting.
   * 
   *  @var BindFlags::GET_NO_CHANGES
   * When set in addition to [flags@Gio.SettingsBindFlags.GET],
   * set the GObject::Object property
   * value initially from the setting, but do not listen for changes of the setting.
   * 
   *  @var BindFlags::INVERT_BOOLEAN
   * When passed to Gio::Settings::bind(),
   * uses a pair of mapping functions that invert
   * the boolean value when mapping between the setting and the property.  The setting and property must both
   * be booleans.  You cannot pass this flag to Gio::Settings::bind_with_mapping().
   */
   /** Flags used when creating a binding.
   * 
   * These flags determine in which direction the binding works. The default is to
   * synchronize in both directions.
   *
   * @ingroup giommEnums
   * @par Bitwise operators:
   * <tt>Settings::BindFlags operator|(Settings::BindFlags, Settings::BindFlags)</tt><br>
   * <tt>Settings::BindFlags operator&(Settings::BindFlags, Settings::BindFlags)</tt><br>
   * <tt>Settings::BindFlags operator^(Settings::BindFlags, Settings::BindFlags)</tt><br>
   * <tt>Settings::BindFlags operator~(Settings::BindFlags)</tt><br>
   * <tt>Settings::BindFlags& operator|=(Settings::BindFlags&, Settings::BindFlags)</tt><br>
   * <tt>Settings::BindFlags& operator&=(Settings::BindFlags&, Settings::BindFlags)</tt><br>
   * <tt>Settings::BindFlags& operator^=(Settings::BindFlags&, Settings::BindFlags)</tt><br>
   */
  enum class BindFlags
  {
    DEFAULT = 0x0,
    GET = (1<<0),
    SET = (1<<1),
    NO_SENSITIVITY = (1<<2),
    GET_NO_CHANGES = (1<<3),
    INVERT_BOOLEAN = (1<<4)
  };


protected:
    explicit Settings(const Glib::ustring& schema_id);

    explicit Settings(const Glib::ustring& schema_id, const Glib::ustring& path);

  //TODO: Requires SettingsBackend: _WRAP_CTOR(Settings(const Glib::ustring& schema_id, const Glib::RefPtr<SettingsBackend>& backend), g_settings_new_with_backend)
  //TODO: Requires SettingsBackend: _WRAP_CTOR(Settings(const Glib::ustring& schema_id, const Glib::RefPtr<SettingsBackend>& backend, const Glib::ustring& path), g_settings_new_with_backend_and_path)
  //TODO: Requires SettingsBackend: _WRAP_CTOR(Settings(const Glib::RefPtr<SettingsSchema>& settings_schema, const Glib::RefPtr<SettingsBackend>& backend, const Glib::ustring& path), g_settings_new_full)

public:
  
  static Glib::RefPtr<Settings> create(const Glib::ustring& schema_id);

  
  static Glib::RefPtr<Settings> create(const Glib::ustring& schema_id, const Glib::ustring& path);

  //TODO: Requires SettingsBackend: _WRAP_CREATE(const Glib::ustring& schema_id, const Glib::RefPtr<SettingsBackend>& backend)
  //TODO: Requires SettingsBackend: _WRAP_CREATE(const Glib::ustring& schema_id, const Glib::RefPtr<SettingsBackend>& backend, const Glib::ustring& path)
  //TODO: Requires SettingsBackend: _WRAP_CREATE(const Glib::RefPtr<SettingsSchema>& settings_schema, const Glib::RefPtr<SettingsBackend>& backend, const Glib::ustring& path)

  //TODO: Rename these to get/set_*_value_variant() and add templated get/set_*_value() methods as elsewhere?
  
  /** Sets @a key in @a settings to @a value.
   * 
   * It is a programmer error to give a @a key that isn’t contained in the
   * schema for @a settings or for @a value to have the incorrect type, per
   * the schema.
   * 
   * If @a value is floating then this function consumes the reference.
   * 
   * @newin{2,26}
   * 
   * @param key The key to set the value for.
   * @param value A Glib::Variant of the correct type.
   * @return True if setting the key succeeded,
   * false if the key was not writable.
   */
  bool set_value(const Glib::ustring& key, const Glib::VariantBase& value);


  /** Gets the value that is stored in the settings for a @a key.
   *
   * It is a programmer error to give a @a key that isn't contained in the
   * schema for the settings.
   *
   * @param key The key to get the value for.
   * @param value A Variant of the expected type.
   *
   * @newin{2,28}
   */
  void get_value(const Glib::ustring& key, Glib::VariantBase& value) const;
  

  //TODO: We've added a bool return to handle the nullptr return value case,
  //but maybe other get_value() methods can return nullptrs too.

  /** Checks the "user value" of a @a key, if there is one.
   *
   * The user value of a key is the last value that was set by the user.
   *
   * After calling reset() this function should always return
   * false (assuming something is not wrong with the system
   * configuration).
   *
   * It is possible that get_value() will return a different
   * value than this method.  This can happen in the case that the user
   * set a value for a key that was subsequently locked down by the system
   * administrator -- this method will return the user's old value.
   *
   * This method may be useful for adding a "reset" option to a UI or
   * for providing indication that a particular value has been changed.
   *
   * It is a programmer error to give a @a key that isn't contained in the
   * schema for the settings.
   *
   * @param key The key to get the user value for.
   * @param value A Variant of the expected type.
   * @result true if a user value was found.
   *
   * @newin{2,40}
   */
  bool get_user_value(const Glib::ustring& key, Glib::VariantBase& value) const;
  

  /** Gets the "default value" of a key.
   *
   * This is the value that would be read if reset() were to be
   * called on the key.
   *
   * Note that this may be a different value than returned by
   * get_default_value() if the system administrator
   * has provided a default value.
   *
   * Comparing the return values of get_default_value() and
   * value() is not sufficient for determining if a value
   * has been set because the user may have explicitly set the value to
   * something that happens to be equal to the default.  The difference
   * here is that if the default changes in the future, the user's key
   * will still be set.
   *
   * This method may be useful for adding an indication to a UI of what
   * the default value was before the user set it.
   *
   * It is a programmer error to give a @a key that isn't contained in the
   * schema for the settings.
   *
   * @param key The key to get the default value for.
   * @param value A Variant of the expected type.
   *
   * @newin{2,40}
   */
  void get_default_value(const Glib::ustring& key, Glib::VariantBase& value) const;
  

  /** Gets the value that is stored at @a key in @a settings.
   * 
   * A convenience variant of Gio::Settings::get() for 32-bit integers.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having an `i` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,26}
   * 
   * @param key The key to get the value for.
   * @return An integer.
   */
  int get_int(const Glib::ustring& key) const;
  
  /** Sets @a key in @a settings to @a value.
   * 
   * A convenience variant of Gio::Settings::set() for 32-bit integers.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having an `i` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,26}
   * 
   * @param key The key to set the value for.
   * @param value The value to set it to.
   * @return True if setting the key succeeded,
   * false if the key was not writable.
   */
  bool set_int(const Glib::ustring& key, int value);
  
  /** Gets the value that is stored at @a key in @a settings.
   * 
   * A convenience variant of Gio::Settings::get() for 64-bit integers.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having an `x` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,50}
   * 
   * @param key The key to get the value for.
   * @return A 64-bit integer.
   */
  gint64 get_int64(const Glib::ustring& key) const;
  
  /** Sets @a key in @a settings to @a value.
   * 
   * A convenience variant of Gio::Settings::set() for 64-bit integers.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having an `x` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,50}
   * 
   * @param key The key to set the value for.
   * @param value The value to set it to.
   * @return True if setting the key succeeded,
   * false if the key was not writable.
   */
  bool set_int64(const Glib::ustring& key, gint64 value);
  
  /** Gets the value that is stored at @a key in @a settings.
   * 
   * A convenience variant of Gio::Settings::get() for 32-bit unsigned
   * integers.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having a `u` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,30}
   * 
   * @param key The key to get the value for.
   * @return An unsigned integer.
   */
  guint get_uint(const Glib::ustring& key) const;
  
  /** Sets @a key in @a settings to @a value.
   * 
   * A convenience variant of Gio::Settings::set() for 32-bit unsigned
   * integers.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having a `u` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,30}
   * 
   * @param key The key to set the value for.
   * @param value The value to set it to.
   * @return True if setting the key succeeded,
   * false if the key was not writable.
   */
  bool set_uint(const Glib::ustring& key, guint value);
  
  /** Gets the value that is stored at @a key in @a settings.
   * 
   * A convenience variant of Gio::Settings::get() for 64-bit unsigned
   * integers.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having a `t` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,50}
   * 
   * @param key The key to get the value for.
   * @return A 64-bit unsigned integer.
   */
  guint64 get_uint64(const Glib::ustring& key) const;
  
  /** Sets @a key in @a settings to @a value.
   * 
   * A convenience variant of Gio::Settings::set() for 64-bit unsigned
   * integers.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having a `t` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,50}
   * 
   * @param key The key to set the value for.
   * @param value The value to set it to.
   * @return True if setting the key succeeded,
   * false if the key was not writable.
   */
  bool set_uint64(const Glib::ustring& key, guint64 value);
  
  /** Gets the value that is stored at @a key in @a settings.
   * 
   * A convenience variant of Gio::Settings::get() for booleans.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having a `b` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,26}
   * 
   * @param key The key to get the value for.
   * @return A boolean.
   */
  bool get_boolean(const Glib::ustring& key) const;
  
  /** Sets @a key in @a settings to @a value.
   * 
   * A convenience variant of Gio::Settings::set() for booleans.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having a `b` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,26}
   * 
   * @param key The key to set the value for.
   * @param value The value to set it to.
   * @return True if setting the key succeeded,
   * false if the key was not writable.
   */
  bool set_boolean(const Glib::ustring& key, bool value);
  
  /** Gets the value that is stored at @a key in @a settings.
   * 
   * A convenience variant of Gio::Settings::get() for strings.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having an `s` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,26}
   * 
   * @param key The key to get the value for.
   * @return A newly-allocated string.
   */
  Glib::ustring get_string(const Glib::ustring& key) const;
  
  /** Sets @a key in @a settings to @a value.
   * 
   * A convenience variant of Gio::Settings::set() for strings.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having an `s` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,26}
   * 
   * @param key The key to set the value for.
   * @param value The value to set it to.
   * @return True if setting the key succeeded,
   * false if the key was not writable.
   */
  bool set_string(const Glib::ustring& key, const Glib::ustring& value);
  
  /** Gets the value that is stored at @a key in @a settings.
   * 
   * A convenience variant of Gio::Settings::get() for doubles.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having a `d` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,26}
   * 
   * @param key The key to get the value for.
   * @return A double.
   */
  double get_double(const Glib::ustring& key) const;
  
  /** Sets @a key in @a settings to @a value.
   * 
   * A convenience variant of Gio::Settings::set() for doubles.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having a `d` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,26}
   * 
   * @param key The key to set the value for.
   * @param value The value to set it to.
   * @return True if setting the key succeeded,
   * false if the key was not writable.
   */
  bool set_double(const Glib::ustring& key, double value);

   
  /** A convenience variant of Gio::Settings::get() for string arrays.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having an `as` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,26}
   * 
   * @param key The key to get the value for.
   * @return A
   * newly-allocated, <tt>nullptr</tt>-terminated array of strings, the value that
   * is stored at @a key in @a settings.
   */
  std::vector<Glib::ustring> get_string_array(const Glib::ustring& key) const;

  
  /** Sets @a key in @a settings to @a value.
   * 
   * A convenience variant of Gio::Settings::set() for string arrays.  If
   *  @a value is <tt>nullptr</tt>, then @a key is set to be the empty array.
   * 
   * It is a programmer error to give a @a key that isn’t specified as
   * having an `as` type in the schema for @a settings (see Glib::VariantType).
   * 
   * @newin{2,26}
   * 
   * @param key The key to set the value for.
   * @param value The value to set it to.
   * @return True if setting the key succeeded,
   * false if the key was not writable.
   */
  bool set_string_array(const Glib::ustring& key, const std::vector<Glib::ustring>& value);

  
  /** Gets the value that is stored in @a settings for @a key and converts it
   * to the enum value that it represents.
   * 
   * In order to use this function the type of the value must be a string
   * and it must be marked in the schema file as an enumerated type.
   * 
   * It is a programmer error to give a @a key that isn’t contained in the
   * schema for @a settings or is not marked as an enumerated type.
   * 
   * If the value stored in the configuration database is not a valid
   * value for the enumerated type then this function will return the
   * default value.
   * 
   * @newin{2,26}
   * 
   * @param key The key to get the value for.
   * @return The enum value.
   */
  int get_enum(const Glib::ustring& key) const;
  
  /** Looks up the enumerated type nick for @a value and writes it to @a key,
   * within @a settings.
   * 
   * It is a programmer error to give a @a key that isn’t contained in the
   * schema for @a settings or is not marked as an enumerated type, or for
   *  @a value not to be a valid value for the named type.
   * 
   * After performing the write, accessing @a key directly with
   * Gio::Settings::get_string() will return the ‘nick’ associated with
   *  @a value.
   * 
   * @param key The key to set the value for.
   * @param value An enumerated value.
   * @return True if the set succeeds, false otherwise.
   */
  bool set_enum(const Glib::ustring& key, int value);
  
  /** Gets the value that is stored in @a settings for @a key and converts it
   * to the flags value that it represents.
   * 
   * In order to use this function the type of the value must be an array
   * of strings and it must be marked in the schema file as a flags type.
   * 
   * It is a programmer error to give a @a key that isn’t contained in the
   * schema for @a settings or is not marked as a flags type.
   * 
   * If the value stored in the configuration database is not a valid
   * value for the flags type then this function will return the default
   * value.
   * 
   * @newin{2,26}
   * 
   * @param key The key to get the value for.
   * @return The flags value.
   */
  guint get_flags(const Glib::ustring& key) const;
  
  /** Looks up the flags type nicks for the bits specified by @a value, puts
   * them in an array of strings and writes the array to @a key, within
   *  @a settings.
   * 
   * It is a programmer error to give a @a key that isn’t contained in the
   * schema for @a settings or is not marked as a flags type, or for @a value
   * to contain any bits that are not value for the named type.
   * 
   * After performing the write, accessing @a key directly with
   * Gio::Settings::get_strv() will return an array of ‘nicks’; one for each
   * bit in @a value.
   * 
   * @param key The key to set the value for.
   * @param value A flags value.
   * @return True if the set succeeds, false otherwise.
   */
  bool set_flags(const Glib::ustring& key, guint value);

  // Ignore varargs functions.
  

  /** Creates a child settings object which has a base path of
   * `base-path/name`, where `base-path` is the base path of
   *  @a settings and `name` is as specified by the caller.
   * 
   * The schema for the child settings object must have been declared
   * in the schema of @a settings using a `<child>` element.
   * 
   * The created child settings object will inherit the
   * Gio::Settings::property_delay_apply() mode from @a settings.
   * 
   * @newin{2,26}
   * 
   * @param name The name of the child schema.
   * @return A ‘child’ settings object.
   */
  Glib::RefPtr<Settings> get_child(const Glib::ustring& name);
  
  /** Creates a child settings object which has a base path of
   * `base-path/name`, where `base-path` is the base path of
   *  @a settings and `name` is as specified by the caller.
   * 
   * The schema for the child settings object must have been declared
   * in the schema of @a settings using a `<child>` element.
   * 
   * The created child settings object will inherit the
   * Gio::Settings::property_delay_apply() mode from @a settings.
   * 
   * @newin{2,26}
   * 
   * @param name The name of the child schema.
   * @return A ‘child’ settings object.
   */
  Glib::RefPtr<const Settings> get_child(const Glib::ustring& name) const;
  
  /** Finds out if a key can be written.
   * 
   * @newin{2,26}
   * 
   * @param name The name of a key.
   * @return True if the key @a name is writable, false otherwise.
   */
  bool is_writable(const Glib::ustring& name) const;

  
  /** Changes the Gio::Settings object into
   * [‘delay-apply’ mode](class.Settings.html#delay-apply-mode).
   * 
   * In this
   * mode, changes to @a settings are not immediately propagated to the
   * backend, but kept locally until Gio::Settings::apply() is called.
   * 
   * @newin{2,26}
   */
  void delay();
  
  /** Applies any changes that have been made to the settings.
   * 
   * This function does nothing unless @a settings is in
   * [‘delay-apply’ mode](class.Settings.html#delay-apply-mode).  In the normal
   * case settings are always applied immediately.
   */
  void apply();
  
  /** Reverts all unapplied changes to the settings.
   * 
   * This function does nothing unless @a settings is in
   * [‘delay-apply’ mode](class.Settings.html#delay-apply-mode).  In the normal
   * case settings are always applied immediately.
   * 
   * Change notifications will be emitted for affected keys.
   */
  void revert();
  
  /** Returns whether the Gio::Settings object has any unapplied
   * changes.
   * 
   * This can only be the case if it is in
   * [‘delay-apply’ mode](class.Settings.html#delay-apply-mode).
   * 
   * @newin{2,26}
   * 
   * @return True if @a settings has unapplied changes, false otherwise.
   */
  bool get_has_unapplied() const;

  
  /** Resets @a key to its default value.
   * 
   * This call resets the key, as much as possible, to its default value.
   * That might be the value specified in the schema or the one set by the
   * administrator.
   * 
   * @param key The name of a key.
   */
  void reset(const Glib::ustring& key);

 
  /** Gets the list of children on @a settings.
   * 
   * The list is exactly the list of strings for which it is not an error
   * to call Gio::Settings::get_child().
   * 
   * There is little reason to call this function from ‘normal’ code, since
   * you should already know what children are in your schema. This function
   * may still be useful there for introspection reasons, however.
   * 
   * You should free the return value with glib_strfreev() when you are done
   * with it.
   * 
   * @return A list of the children
   * on @a settings, in no defined order.
   */
  std::vector<Glib::ustring> list_children() const;
  

  /** Create a binding between the @a key in the @a settings object
   * and the property @a property of @a object.
   * 
   * The binding uses the default GIO mapping functions to map
   * between the settings and property values. These functions
   * handle booleans, numeric types and string types in a
   * straightforward way. Use Gio::Settings::bind_with_mapping() if
   * you need a custom mapping, or map between types that are not
   * supported by the default mapping functions.
   * 
   * Unless the @a flags include [flags@Gio.SettingsBindFlags.NO_SENSITIVITY], this
   * function also establishes a binding between the writability of
   *  @a key and the `sensitive` property of @a object (if @a object has
   * a boolean property by that name). See Gio::Settings::bind_writable()
   * for more details about writable bindings.
   * 
   * Note that the lifecycle of the binding is tied to @a object,
   * and that you can have only one binding per object property.
   * If you bind the same property twice on the same object, the second
   * binding overrides the first one.
   * 
   * @newin{2,26}
   * 
   * @param key The key to bind.
   * @param object The object with property to bind.
   * @param property The name of the property to bind.
   * @param flags Flags for the binding.
   */
  void bind(const Glib::ustring& key, Glib::ObjectBase* object, const Glib::ustring& property, BindFlags flags =  BindFlags::DEFAULT);

  /** Create a binding between the @a key in the @a settings object
   * and the @a property_proxy.
   *
   * The binding uses the default GIO mapping functions to map
   * between the settings and property values. These functions
   * handle booleans, numeric types and string types in a
   * straightforward way. Use g_settings_bind_with_mapping() if
   * you need a custom mapping, or map between types that are not
   * supported by the default mapping functions.
   *
   * Unless the @a flags include Gio::Settings::BindFlags::NO_SENSITIVITY, this
   * function also establishes a binding between the writability of
   * @a key and the "sensitive" property of @a object (if @a object has
   * a boolean property by that name). See bind_writable()
   * for more details about writable bindings.
   *
   * Note that the lifecycle of the binding is tied to @a object,
   * and that you can have only one binding per object property.
   * If you bind the same property twice on the same object, the second
   * binding overrides the first one.
   *
   * @param key The key to bind.
   * @param property_proxy The property to bind.
   * @param flags Flags for the binding.
   */
  void bind(const Glib::ustring& key, const Glib::PropertyProxy_Base& property_proxy, BindFlags flags = BindFlags::DEFAULT);

  /** A slot to be called to map values in a binding.
   *
   * For instance:
   * @code
   *   std::optional<int> map_ustring_to_int(const Glib::ustring& from_string);
   * @endcode
   *
   * @return A value of type <tt>T_to</tt> if the mapping was successful,
   * and an empty optional with no value (i.e. <tt>std::nullopt</tt>) otherwise.
   */
  template <typename T_from, typename T_to>
  using SlotTypedMapping = sigc::slot<std::optional<T_to>(const T_from&)>;

  // Gio::Settings::bind() is similar to Glib::Binding::bind_property().
  /** Create a binding between the @a key in the @a settings object
   * and the property @a property of @a object.
   *
   * The binding uses the provided mapping functions to map between
   * settings and property values.
   *
   * Note that the lifecycle of the binding is tied to @a object,
   * and that you can have only one binding per object property.
   * If you bind the same property twice on the same object, the second
   * binding overrides the first one.
   *
   * The template parameters <tt>T_setting</tt> and <tt>T_property</tt> must be
   * explicitly specified in each call. The compiler can't deduce them.
   * For instance:
   * @code
   *  m_settings->bind<Glib::ustring, unsigned int>("transition",
   *    m_transition, "selected", Gio::Settings::BindFlags::DEFAULT,
   *    sigc::mem_fun(*this, &ExampleAppPrefs::map_from_ustring_to_int),
   *    sigc::mem_fun(*this, &ExampleAppPrefs::map_from_int_to_ustring));
   * @endcode
   *
   * @newin{2,76}
   *
   * @param key The key to bind.
   * @param object A Glib::ObjectBase.
   * @param property The name of the property to bind.
   * @param flags Flags for the binding.
   * @param slot_get_mapping A function that gets called to convert values from
   *        setting to parameter, or an empty slot to use the default GIO mapping.
   * @param slot_set_mapping A function that gets called to convert values from
   *        parameter to setting, or an empty slot to use the default GIO mapping.
   *
   * @tparam T_setting Type of the setting. Must be a type that can be
   *         stored in a Glib::Variant<T_setting> object.
   * @tparam T_property Type of the property. Must be a type that can be
   *         stored in a Glib::Value<T_property> object.
   */
  template <typename T_setting, typename T_property>
  void bind(const Glib::ustring& key,
    Glib::ObjectBase* object, const Glib::ustring& property, BindFlags flags,
    const SlotTypedMapping<T_setting, T_property>& slot_get_mapping,
    const SlotTypedMapping<T_property, T_setting>& slot_set_mapping)
  {
    return bind_value(key, object, property, flags,
      slot_get_mapping.empty() ? SlotGetMapping() : GetMappingProp<T_setting, T_property>(slot_get_mapping),
      slot_set_mapping.empty() ? SlotSetMapping() : SetMappingProp<T_property, T_setting>(slot_set_mapping));
  }

  /** Create a binding between the @a key in the @a settings object
   * and the @a property_proxy.
   *
   * The binding uses the provided mapping functions to map between
   * settings and property values.
   *
   * Note that the lifecycle of the binding is tied to @a property_proxy's
   * object, and that you can have only one binding per object property.
   * If you bind the same property twice on the same object, the second
   * binding overrides the first one.
   *
   * The template parameters <tt>T_setting</tt> and <tt>T_property</tt> must be
   * explicitly specified in each call. The compiler can't deduce them.
   * For instance:
   * @code
   *  m_settings->bind<Glib::ustring, unsigned int>("transition",
   *    m_transition->property_selected(), Gio::Settings::BindFlags::DEFAULT,
   *    sigc::mem_fun(*this, &ExampleAppPrefs::map_from_ustring_to_int),
   *    sigc::mem_fun(*this, &ExampleAppPrefs::map_from_int_to_ustring));
   * @endcode
   *
   * @newin{2,76}
   *
   * @param key The key to bind.
   * @param property_proxy The property to bind.
   * @param flags Flags for the binding.
   * @param slot_get_mapping A function that gets called to convert values from
   *        setting to parameter, or an empty slot to use the default GIO mapping.
   * @param slot_set_mapping A function that gets called to convert values from
   *        parameter to setting, or an empty slot to use the default GIO mapping.
   *
   * @tparam T_setting Type of the setting. Must be a type that can be
   *         stored in a Glib::Variant<T_setting> object.
   * @tparam T_property Type of the property. Must be a type that can be
   *         stored in a Glib::Value<T_property> object.
   */
  template <typename T_setting, typename T_property>
  void bind(const Glib::ustring& key,
    const Glib::PropertyProxy_Base& property_proxy, BindFlags flags,
    const SlotTypedMapping<T_setting, T_property>& slot_get_mapping,
    const SlotTypedMapping<T_property, T_setting>& slot_set_mapping)
  {
    bind<T_setting, T_property>(key, property_proxy.get_object(),
      property_proxy.get_name(), flags, slot_get_mapping, slot_set_mapping);
  }
  

  /** Create a binding between the writability of @a key in the
   *  @a settings object and the property @a property of @a object.
   * 
   * The property must be boolean; `sensitive` or `visible`
   * properties of widgets are the most likely candidates.
   * 
   * Writable bindings are always uni-directional; changes of the
   * writability of the setting will be propagated to the object
   * property, not the other way.
   * 
   * When the @a inverted argument is true, the binding inverts the
   * value as it passes from the setting to the object, i.e. @a property
   * will be set to true if the key is not writable.
   * 
   * Note that the lifecycle of the binding is tied to @a object,
   * and that you can have only one binding per object property.
   * If you bind the same property twice on the same object, the second
   * binding overrides the first one.
   * 
   * @newin{2,26}
   * 
   * @param key The key to bind.
   * @param object The object with property to bind.
   * @param property The name of a boolean property to bind.
   * @param inverted Whether to ‘invert’ the value.
   */
  void bind_writable(const Glib::ustring& key, Glib::ObjectBase* object, const Glib::ustring& property, bool inverted = false);

  /** Create a binding between the writability of @a key in the
   * @a settings object and the @a property_proxy.
   *
   * The property must be boolean; "sensitive" or "visible"
   * properties of widgets are the most likely candidates.
   *
   * Writable bindings are always uni-directional; changes of the
   * writability of the setting will be propagated to the object
   * property, not the other way.
   *
   * When the @a inverted argument is <tt>true</tt>, the binding inverts the
   * value as it passes from the setting to the object, i.e. the property
   * will be set to <tt>true</tt> if the key is not writable.
   *
   * Note that the lifecycle of the binding is tied to @a object,
   * and that you can have only one binding per object property.
   * If you bind the same property twice on the same object, the second
   * binding overrides the first one.
   *
   * @param key The key to bind.
   * @param property_proxy The boolean property to bind.
   * @param inverted Whether to 'invert' the value.
   */
  void bind_writable(const Glib::ustring& key, const Glib::PropertyProxy_Base& property_proxy, bool inverted=false);

  
  /** Removes an existing binding for @a property on @a object.
   * 
   * Note that bindings are automatically removed when the
   * object is finalized, so it is rarely necessary to call this
   * function.
   * 
   * @newin{2,76}
   * 
   * @param object The object with property to unbind.
   * @param property The property whose binding is removed.
   */
  static void unbind(Glib::ObjectBase* object, const Glib::ustring& property);

  /** Removes an existing binding for @a property_proxy.
   *
   * Note that bindings are automatically removed when the
   * object is finalized, so it is rarely necessary to call this
   * function.
   *
   * @newin{2,76}
   *
   * @param property_proxy The property whose binding is removed.
   */
  static void unbind(const Glib::PropertyProxy_Base& property_proxy);

  
  /** Creates a Gio::Action corresponding to a given Gio::Settings key.
   * 
   * The action has the same name as the key.
   * 
   * The value of the key becomes the state of the action and the action
   * is enabled when the key is writable.  Changing the state of the
   * action results in the key being written to.  Changes to the value or
   * writability of the key cause appropriate change notifications to be
   * emitted for the action.
   * 
   * For boolean-valued keys, action activations take no parameter and
   * result in the toggling of the value.  For all other types,
   * activations take the new value for the key (which must have the
   * correct type).
   * 
   * @newin{2,32}
   * 
   * @param key The name of a key in @a settings.
   * @return A new Gio::Action.
   */
  Glib::RefPtr<Action> create_action(const Glib::ustring& key);

  //TODO?: _WRAP_PROPERTY("backend", Glib::RefPtr<SettingsBackend>)

  /** Whether the Gio::Settings object is in
   * [‘delay-apply’ mode](class.Settings.html#delay-apply-mode).
   * 
   * @newin{2,28}
   *
   * Default value: <tt>false</tt>
   *
   * @return A PropertyProxy_ReadOnly that allows you to get the value of the property,
   * or receive notification when the value of the property changes.
   */
  Glib::PropertyProxy_ReadOnly< bool > property_delay_apply() const;


  /** Whether the Gio::Settings object has outstanding changes.
   * 
   * These changes will be applied when Gio::Settings::apply() is called.
   *
   * Default value: <tt>false</tt>
   *
   * @return A PropertyProxy_ReadOnly that allows you to get the value of the property,
   * or receive notification when the value of the property changes.
   */
  Glib::PropertyProxy_ReadOnly< bool > property_has_unapplied() const;


  /** The path within the backend where the settings are stored.
   *
   * Default value: ""
   *
   * @return A PropertyProxy_ReadOnly that allows you to get the value of the property,
   * or receive notification when the value of the property changes.
   */
  Glib::PropertyProxy_ReadOnly< std::string > property_path() const;


  /** The name of the schema that describes the types of keys
   * for this Gio::Settings object.
   *
   * Default value: ""
   *
   * @return A PropertyProxy_ReadOnly that allows you to get the value of the property,
   * or receive notification when the value of the property changes.
   */
  Glib::PropertyProxy_ReadOnly< Glib::ustring > property_schema_id() const;


  /** The Gio::SettingsSchema describing the types of keys for this
   * Gio::Settings object.
   * 
   * Ideally, this property would be called Gio::Settings::property_schema().
   * Gio::SettingsSchema
   * has only existed since version 2.32, however, and before then the
   * Gio::Settings::property_schema() property was used to refer to the ID of the schema rather
   * than the schema itself.  Take care.
   * 
   * @newin{2,58}
   *
   * @return A PropertyProxy_ReadOnly that allows you to get the value of the property,
   * or receive notification when the value of the property changes.
   */
  Glib::PropertyProxy_ReadOnly< Glib::RefPtr<SettingsSchema> > property_settings_schema() const;


  //TODO?: _WRAP_SIGNAL(bool change_event(const std::vector<Glib::QueryQuark>&  keys, int n_keys), "change-event")

 
  /**
   * @par Slot Prototype:
   * <tt>void on_my_%changed(const Glib::ustring& key)</tt>
   *
   * Flags: Run Last
   *
   * Emitted when a key has potentially changed.
   * 
   * You should call one of the Gio::Settings::get() calls to check the new
   * value.
   * 
   * This signal supports detailed connections.  You can connect to the
   * detailed signal `changed::x` in order to only receive callbacks
   * when key `x` changes.
   * 
   * Note that @a settings only emits this signal if you have read @a key at
   * least once while a signal handler was already connected for @a key.
   * 
   * @param key The name of the key that changed.
   */

  Glib::SignalProxyDetailed<void(const Glib::ustring&)> signal_changed(const Glib::ustring& key = {});


  /**
   * @par Slot Prototype:
   * <tt>bool on_my_%writable_change_event(GQuark key)</tt>
   *
   * Flags: Run Last
   *
   * Emitted once per writability change event that affects this settings object.
   * 
   * You should connect
   * to this signal if you are interested in viewing groups of changes
   * before they are split out into multiple emissions of the
   * Gio::Settings::signal_writable_changed() signal.  For most use cases it is more
   * appropriate to use the Gio::Settings::signal_writable_changed() signal.
   * 
   * In the event that the writability change applies only to a single
   * key, @a key will be set to the [alias@GLib.Quark] for that key.  In the event
   * that the writability change affects the entire settings object,
   *  @a key will be `0`.
   * 
   * The default handler for this signal invokes the Gio::Settings::signal_writable_changed()
   * and Gio::Settings::signal_changed() signals for each affected key.  This is done because
   * changes in writability might also imply changes in value (if for
   * example, a new mandatory setting is introduced).  If any other
   * connected handler returns true then this default functionality
   * will be suppressed.
   * 
   * @param key The quark of the key, or `0`.
   * @return True to stop other handlers from being invoked for the
   * event, false to propagate the event further.
   */

  Glib::SignalProxy<bool(GQuark)> signal_writable_change_event();

  
  /**
   * @par Slot Prototype:
   * <tt>void on_my_%writable_changed(const Glib::ustring& key)</tt>
   *
   * Flags: Run Last
   *
   * Emitted when the writability of a key has potentially changed.
   * 
   * You should call Gio::Settings::is_writable() in order to determine the
   * new status.
   * 
   * This signal supports detailed connections.  You can connect to the
   * detailed signal `writable-changed::x` in order to only receive
   * callbacks when the writability of `x` changes.
   * 
   * @param key The key.
   */

  Glib::SignalProxyDetailed<void(const Glib::ustring&)> signal_writable_changed(const Glib::ustring& key = {});


#ifndef DOXYGEN_SHOULD_SKIP_THIS
  // SlotGetMapping and SlotSetMapping must be public. They are used in
  // the anonymous namespace in settings.ccg.
  /* A slot to be called to map values in a binding created by bind_value().
   *
   * For instance:
   * @code
   *   bool map_from_setting_to_property(GValue* to_value, GVariant* from_variant);
   * @endcode
   *
   * @return <tt>true</tt> if the mapping was successful, and <tt>false</tt> otherwise.
   */
  using SlotGetMapping = sigc::slot<bool(GValue*, GVariant*)>;

  /* A slot to be called to map values in a binding created by bind_value().
   *
   * For instance:
   * @code
   *   GVariant* map_from_property_to_setting(
   *     const GValue* from_value, const GVariantType* expected_type);
   * @endcode
   *
   * @return A new <tt>GVariant</tt> if the mapping was successful,
   *         and <tt>nullptr</tt> otherwise.
   */
  using SlotSetMapping = sigc::slot<GVariant*(const GValue*, const GVariantType*)>;
#endif // DOXYGEN_SHOULD_SKIP_THIS

private:
  void bind_value(const Glib::ustring& key,
    Glib::ObjectBase* object, const Glib::ustring& property, BindFlags flags,
    const SlotGetMapping& get_mapping, const SlotSetMapping& set_mapping);

  // The functor GetMappingProp can be implicitly converted to a SlotGetMapping
  // and used in a call to bind_value().
  template <typename T_from, typename T_to>
  class GetMappingProp
  {
  public:
    explicit GetMappingProp(const SlotTypedMapping<T_from, T_to>& slot) : typed_mapping(slot) {}

    bool operator()(GValue* to_value, GVariant* from_variant)
    {
      Glib::Variant<T_from> from_glib_variant(from_variant, true);
      const auto to = typed_mapping(from_glib_variant.get());

      if (!to.has_value())
        return false;

      Glib::Value<T_to> to_glib_value;
      to_glib_value.init(to_value);
      to_glib_value.set(*to);
      g_value_copy(to_glib_value.gobj(), to_value);
      return true;
    }

  private:
    SlotTypedMapping<T_from, T_to> typed_mapping;
  }; // Settings::GetMappingProp

  // The functor SetMappingProp can be implicitly converted to a SlotGetMapping
  // and used in a call to bind_value().
  template <typename T_from, typename T_to>
  class SetMappingProp
  {
  public:
    explicit SetMappingProp(const SlotTypedMapping<T_from, T_to>& slot) : typed_mapping(slot) {}

    GVariant* operator()(const GValue* from_value, const GVariantType* /* expected_type */)
    {
      Glib::Value<T_from> from_glib_value;
      from_glib_value.init(from_value);
      const auto to = typed_mapping(from_glib_value.get());

      if (!to.has_value())
        return nullptr;

      auto to_glib_variant = Glib::Variant<T_to>::create(*to);
      return to_glib_variant.gobj_copy();
    }

  private:
    SlotTypedMapping<T_from, T_to> typed_mapping;
  }; // Settings::SetMappingProp


public:

public:
  //C++ methods used to invoke GTK+ virtual functions:

protected:
  //GTK+ Virtual Functions (override these to change behaviour):

  //Default Signal Handlers::
  /// This is a default handler for the signal signal_changed().
  virtual void on_changed(const Glib::ustring& key);
  /// This is a default handler for the signal signal_writable_change_event().
  virtual bool on_writable_change_event(GQuark key);
  /// This is a default handler for the signal signal_writable_changed().
  virtual void on_writable_changed(const Glib::ustring& key);


}; // Settings

} // namespace Gio

namespace Gio
{

/** @ingroup giommEnums */
inline Settings::BindFlags operator|(Settings::BindFlags lhs, Settings::BindFlags rhs)
  { return static_cast<Settings::BindFlags>(static_cast<unsigned>(lhs) | static_cast<unsigned>(rhs)); }

/** @ingroup giommEnums */
inline Settings::BindFlags operator&(Settings::BindFlags lhs, Settings::BindFlags rhs)
  { return static_cast<Settings::BindFlags>(static_cast<unsigned>(lhs) & static_cast<unsigned>(rhs)); }

/** @ingroup giommEnums */
inline Settings::BindFlags operator^(Settings::BindFlags lhs, Settings::BindFlags rhs)
  { return static_cast<Settings::BindFlags>(static_cast<unsigned>(lhs) ^ static_cast<unsigned>(rhs)); }

/** @ingroup giommEnums */
inline Settings::BindFlags operator~(Settings::BindFlags flags)
  { return static_cast<Settings::BindFlags>(~static_cast<unsigned>(flags)); }

/** @ingroup giommEnums */
inline Settings::BindFlags& operator|=(Settings::BindFlags& lhs, Settings::BindFlags rhs)
  { return (lhs = static_cast<Settings::BindFlags>(static_cast<unsigned>(lhs) | static_cast<unsigned>(rhs))); }

/** @ingroup giommEnums */
inline Settings::BindFlags& operator&=(Settings::BindFlags& lhs, Settings::BindFlags rhs)
  { return (lhs = static_cast<Settings::BindFlags>(static_cast<unsigned>(lhs) & static_cast<unsigned>(rhs))); }

/** @ingroup giommEnums */
inline Settings::BindFlags& operator^=(Settings::BindFlags& lhs, Settings::BindFlags rhs)
  { return (lhs = static_cast<Settings::BindFlags>(static_cast<unsigned>(lhs) ^ static_cast<unsigned>(rhs))); }
} // namespace Gio

#ifndef DOXYGEN_SHOULD_SKIP_THIS
namespace Glib
{

template <>
class GIOMM_API Value<Gio::Settings::BindFlags> : public Glib::Value_Flags<Gio::Settings::BindFlags>
{
public:
  static GType value_type() G_GNUC_CONST;
};

} // namespace Glib
#endif /* DOXYGEN_SHOULD_SKIP_THIS */


namespace Glib
{
  /** A Glib::wrap() method for this object.
   *
   * @param object The C instance.
   * @param take_copy False if the result should take ownership of the C instance. True if it should take a new copy or ref.
   * @result A C++ instance that wraps this C instance.
   *
   * @relates Gio::Settings
   */
  GIOMM_API
  Glib::RefPtr<Gio::Settings> wrap(GSettings* object, bool take_copy = false);
}


#endif /* _GIOMM_SETTINGS_H */

