The Glib.Settings_Backend.Gsettings_Backend interface defines a generic interface for non-strictly-typed data that is stored in a hierarchy. To implement an alternative storage backend for Glib.Settings.Gsettings, you need to implement the Glib.Settings_Backend.Gsettings_Backend interface and then make it implement the extension point G_SETTINGS_BACKEND_EXTENSION_POINT_NAME.
The interface defines methods for reading and writing values, a method for determining if writing of certain values will fail (lockdown) and a change notification mechanism.
The semantics of the interface are very precisely defined and implementations must carefully adhere to the expectations of callers that are documented on each of the interface methods.
Some of the Glib.Settings_Backend.Gsettings_Backend functions accept or return a Gtree.Gtree. These trees always have strings as keys and Glib.Variant.Gvariant as values. g_settings_backend_create_tree is a convenience function to create suitable trees.
The Glib.Settings_Backend.Gsettings_Backend API is exported to allow third-party implementations, but does not carry the same stability guarantees as the public GIO API. For this reason, you have to define the C preprocessor symbol G_SETTINGS_ENABLE_BACKEND before including gio/gsettingsbackend.h.
<group>GIO</group> <gtkada_demo>create_settings.adb</gtkada_demo>
procedure Changed
(Self : not null access Gsettings_Backend_Record;
Key : UTF8_String;
Origin_Tag : System.Address)
Signals that a single key has possibly changed. Backend implementations should call this if a key has possibly changed its value. Key must be a valid key (ie starting with a slash, not containing '//', and not ending with a slash). The implementation must call this function during any call to g_settings_backend_write, before the call returns (except in the case that no keys are actually changed and it cares to detect this fact). It may not rely on the existence of a mainloop for dispatching the signal later. The implementation may call this function at any other time it likes in response to other events (such as changes occurring outside of the program). These calls may originate from a mainloop or may originate in response to any other action (including from calls to g_settings_backend_write). In the case that this call is in response to a call to g_settings_backend_write then Origin_Tag must be set to the same value that was passed to that call. Since: gtk+ 2.26
the name of the key
the origin tag
function Get_Default return Gsettings_Backend
Returns the default Glib.Settings_Backend.Gsettings_Backend. It is possible to override the default by setting the GSETTINGS_BACKEND environment variable to the name of a settings backend. The user gets a reference to the backend. Since: gtk+ 2.28
the default Glib.Settings_Backend.Gsettings_Backend, which will be a dummy (memory) settings backend if no other settings backend is available. Has transfer-ownership='full'.
function Get_Type return Glib.GType
type Gsettings_Backend is access all Gsettings_Backend_Record'Class;
type Gsettings_Backend_Record is new GObject_Record with null record;
procedure Keys_Changed
(Self : not null access Gsettings_Backend_Record;
Path : UTF8_String;
Items : GNAT.Strings.String_List;
Origin_Tag : System.Address)
Signals that a list of keys have possibly changed. Backend implementations should call this if keys have possibly changed their values. Path must be a valid path (ie starting and ending with a slash and not containing '//'). Each string in Items must form a valid key name when Path is prefixed to it (ie: each item must not start or end with '/' and must not contain '//'). The meaning of this signal is that any of the key names resulting from the contatenation of Path with each item in Items may have changed. The same rules for when notifications must occur apply as per Glib.Settings_Backend.Changed. These two calls can be used interchangeably if exactly one item has changed (although in that case Glib.Settings_Backend.Changed is definitely preferred). For efficiency reasons, the implementation should strive for Path to be as long as possible (ie: the longest common prefix of all of the keys that were changed) but this is not strictly required. Since: gtk+ 2.26
the path containing the changes
the null-terminated list of changed keys
the origin tag
function Memory_New return Gsettings_Backend
Creates a private, nonpersistent back end. Unref when finished.
procedure Path_Changed
(Self : not null access Gsettings_Backend_Record;
Path : UTF8_String;
Origin_Tag : System.Address)
Signals that all keys below a given path may have possibly changed. Backend implementations should call this if an entire path of keys have possibly changed their values. Path must be a valid path (ie starting and ending with a slash and not containing '//'). The meaning of this signal is that any of the key which has a name starting with Path may have changed. The same rules for when notifications must occur apply as per Glib.Settings_Backend.Changed. This call might be an appropriate reasponse to a 'reset' call but implementations are also free to explicitly list the keys that were affected by that call if they can easily do so. For efficiency reasons, the implementation should strive for Path to be as long as possible (ie: the longest common prefix of all of the keys that were changed) but this is not strictly required. As an example, if this function is called with the path of "/" then every single key in the application will be notified of a possible change. Since: gtk+ 2.26
the path containing the changes
the origin tag
procedure Path_Writable_Changed
(Self : not null access Gsettings_Backend_Record;
Path : UTF8_String)
Signals that the writability of all keys below a given path may have changed. Since GSettings performs no locking operations for itself, this call will always be made in response to external events. Since: gtk+ 2.26
the name of the path
procedure Writable_Changed
(Self : not null access Gsettings_Backend_Record;
Key : UTF8_String)
Signals that the writability of a single key has possibly changed. Since GSettings performs no locking operations for itself, this call will always be made in response to external events. Since: gtk+ 2.26
the name of the key