class: SettingsBackend

[27:7] extends: object

The GSettingsBackend interface defines a generic interface for non-strictly-typed data that is stored in a hierarchy. To implement an alternative storage backend for [class@Gio.Settings], you need to implement the GSettingsBackend 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 GSettingsBackend functions accept or return a [struct@GLib.Tree]. These trees always have strings as keys and [struct@GLib.Variant] as values. The GSettingsBackend 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.

Members

• handleObj
• lib
• retainedCallbacks
• signalHandlerNames
• signalSetterHandlers

Methods

• SettingsBackend (Handle = null)

  Creates a new SettingsBackend by wrapping a native handle or another wrapper.

  • @p Handle is the native handle or another wrapper whose handle to adopt.

• toNativeHandle (Source)

  Normalizes a constructor argument into a raw pointer carrier. Accepts a raw NativeHandle, a raw NativeBuffer returned from fn.call(...), another generated wrapper exposing handle(), or null. Returns null when the argument carries no pointer.

  • @p Source is the raw handle, raw buffer, wrapper, or null.
  • @r A raw pointer carrier or null when no pointer is present.

• getLib ()

  Returns the opened native library for this generated wrapper.

  • @r The opened native library.

• handle ()

  Returns the wrapped NativeHandle.

  • @r The wrapped NativeHandle.

• isNull ()

  Returns true when the wrapped handle is null.

  • @r A bool.

• describe ()

  Returns a small string for debugging generated wrappers.

  • @r A string.

• asObject ()

  Wraps this handle as Object.

  • @r A Object object.

• changed (string key, origin_tag)

  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.

  • @p key is the name of the key.
  • @p origin_tag is the origin tag.
  • @r None.

• changed_tree (object tree, origin_tag)

  This call is a convenience wrapper. It gets the list of changes from

  • @tree, computes the longest common prefix and calls g_settings_backend_changed().
  • @p tree is a #GTree containing the changes.
  • @p origin_tag is the origin tag.
  • @r None.

• keys_changed (string path, list items, origin_tag)

  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 concatenation of @path with each item in @items may have changed. The same rules for when notifications must occur apply as per g_settings_backend_changed(). These two calls can be used interchangeably if exactly one item has changed (although in that case g_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.

  • @p path is the path containing the changes.
  • @p items is the %NULL-terminated list of changed keys.
  • @p origin_tag is the origin tag.
  • @r None.

• path_changed (string path, origin_tag)

  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 g_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.

  • @p path is the path containing the changes.
  • @p origin_tag is the origin tag.
  • @r None.

• path_writable_changed (string path)

  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.

  • @p path is the name of the path.
  • @r None.

• writable_changed (string key)

  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.

  • @p key is the name of the key.
  • @r None.