Copyright | Will Thompson Iñaki García Etxebarria and Jonas Platte |
---|---|
License | LGPL-2.1 |
Maintainer | Iñaki García Etxebarria (inaki@blueleaf.cc) |
Safe Haskell | None |
Language | Haskell2010 |
The SettingsBackend
interface defines a generic interface for
non-strictly-typed data that is stored in a hierarchy. To implement
an alternative storage backend for Settings
, you need to implement
the SettingsBackend
interface and then make it implement the
extension point 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 SettingsBackend
functions accept or return a Tree
.
These trees always have strings as keys and GVariant
as values.
g_settings_backend_create_tree()
is a convenience function to create
suitable trees.
The SettingsBackend
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
.
Synopsis
- newtype SettingsBackend = SettingsBackend (ManagedPtr SettingsBackend)
- class (GObject o, IsDescendantOf SettingsBackend o) => IsSettingsBackend o
- toSettingsBackend :: (MonadIO m, IsSettingsBackend o) => o -> m SettingsBackend
- noSettingsBackend :: Maybe SettingsBackend
- settingsBackendChanged :: (HasCallStack, MonadIO m, IsSettingsBackend a) => a -> Text -> Ptr () -> m ()
- settingsBackendChangedTree :: (HasCallStack, MonadIO m, IsSettingsBackend a) => a -> Tree -> Ptr () -> m ()
- settingsBackendGetDefault :: (HasCallStack, MonadIO m) => m SettingsBackend
- settingsBackendKeysChanged :: (HasCallStack, MonadIO m, IsSettingsBackend a) => a -> Text -> [Text] -> Ptr () -> m ()
- settingsBackendPathChanged :: (HasCallStack, MonadIO m, IsSettingsBackend a) => a -> Text -> Ptr () -> m ()
- settingsBackendPathWritableChanged :: (HasCallStack, MonadIO m, IsSettingsBackend a) => a -> Text -> m ()
- settingsBackendWritableChanged :: (HasCallStack, MonadIO m, IsSettingsBackend a) => a -> Text -> m ()
Exported types
newtype SettingsBackend Source #
Memory-managed wrapper type.
Instances
GObject SettingsBackend Source # | |
Defined in GI.Gio.Objects.SettingsBackend gobjectType :: IO GType # | |
HasParentTypes SettingsBackend Source # | |
Defined in GI.Gio.Objects.SettingsBackend | |
type ParentTypes SettingsBackend Source # | |
Defined in GI.Gio.Objects.SettingsBackend |
class (GObject o, IsDescendantOf SettingsBackend o) => IsSettingsBackend o Source #
Type class for types which can be safely cast to SettingsBackend
, for instance with toSettingsBackend
.
Instances
(GObject o, IsDescendantOf SettingsBackend o) => IsSettingsBackend o Source # | |
Defined in GI.Gio.Objects.SettingsBackend |
toSettingsBackend :: (MonadIO m, IsSettingsBackend o) => o -> m SettingsBackend Source #
Cast to SettingsBackend
, for types for which this is known to be safe. For general casts, use castTo
.
noSettingsBackend :: Maybe SettingsBackend Source #
A convenience alias for Nothing
:: Maybe
SettingsBackend
.
Methods
changed
settingsBackendChanged Source #
:: (HasCallStack, MonadIO m, IsSettingsBackend a) | |
=> a |
|
-> Text |
|
-> Ptr () |
|
-> m () |
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 originTag
must be set to the same
value that was passed to that call.
Since: 2.26
changedTree
settingsBackendChangedTree Source #
:: (HasCallStack, MonadIO m, IsSettingsBackend a) | |
=> a |
|
-> Tree |
|
-> Ptr () |
|
-> m () |
This call is a convenience wrapper. It gets the list of changes from
tree
, computes the longest common prefix and calls
settingsBackendChanged
.
Since: 2.26
getDefault
settingsBackendGetDefault Source #
:: (HasCallStack, MonadIO m) | |
=> m SettingsBackend | Returns: the default |
Returns the default SettingsBackend
. 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: 2.28
keysChanged
settingsBackendKeysChanged Source #
:: (HasCallStack, MonadIO m, IsSettingsBackend a) | |
=> a |
|
-> Text |
|
-> [Text] |
|
-> Ptr () |
|
-> m () |
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
settingsBackendChanged
. These two calls can be used
interchangeably if exactly one item has changed (although in that
case settingsBackendChanged
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: 2.26
pathChanged
settingsBackendPathChanged Source #
:: (HasCallStack, MonadIO m, IsSettingsBackend a) | |
=> a |
|
-> Text |
|
-> Ptr () |
|
-> m () |
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
settingsBackendChanged
. 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: 2.26
pathWritableChanged
settingsBackendPathWritableChanged Source #
:: (HasCallStack, MonadIO m, IsSettingsBackend a) | |
=> a |
|
-> Text |
|
-> m () |
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: 2.26
writableChanged
settingsBackendWritableChanged Source #
:: (HasCallStack, MonadIO m, IsSettingsBackend a) | |
=> a |
|
-> Text |
|
-> m () |
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: 2.26