GI.Gio.Objects.PropertyAction

A PropertyAction is a way to get a Action with a state value reflecting and controlling the value of a Object property.

The state of the action will correspond to the value of the property. Changing it will change the property (assuming the requested value matches the requirements as specified in the ParamSpec).

Only the most common types are presently supported. Booleans are mapped to booleans, strings to strings, signed/unsigned integers to int32/uint32 and floats and doubles to doubles.

If the property is an enum then the state will be string-typed and conversion will automatically be performed between the enum value and "nick" string as per the EnumValue table.

Flags types are not currently supported.

Properties of object types, boxed types and pointer types are not supported and probably never will be.

Properties of GVariant types are not currently supported.

If the property is boolean-valued then the action will have a NULL parameter type, and activating the action (with no parameter) will toggle the value of the property.

In all other cases, the parameter type will correspond to the type of the property.

The general idea here is to reduce the number of locations where a particular piece of state is kept (and therefore has to be synchronised between). PropertyAction does not have a separate state that is kept in sync with the property value -- its state is the property value.

For example, it might be useful to create a Action corresponding to the "visible-child-name" property of a GtkStack so that the current page can be switched from a menu. The active radio indication in the menu is then directly determined from the active page of the GtkStack.

An anti-example would be binding the "active-id" property on a GtkComboBox. This is because the state of the combobox itself is probably uninteresting and is actually being used to control something else.

Another anti-example would be to bind to the "visible-child-name" property of a GtkStack if this value is actually stored in Settings. In that case, the real source of the value is Settings. If you want a Action to control a setting stored in Settings, see settingsCreateAction instead, and possibly combine its use with settingsBind.

Since: 2.38

Exported types

newtype PropertyAction

Memory-managed wrapper type.

Constructors

PropertyAction (ManagedPtr PropertyAction)

Instances

GObject PropertyAction

Defined in GI.Gio.Objects.PropertyAction

Methods

gobjectType :: IO GType

HasParentTypes PropertyAction

Defined in GI.Gio.Objects.PropertyAction

type ParentTypes PropertyAction

Defined in GI.Gio.Objects.PropertyAction

type ParentTypes PropertyAction = Object ': (Action ': ([] :: [Type]))

class (GObject o, IsDescendantOf PropertyAction o) => IsPropertyAction o

Type class for types which can be safely cast to PropertyAction, for instance with toPropertyAction.

Instances

(GObject o, IsDescendantOf PropertyAction o) => IsPropertyAction o

Defined in GI.Gio.Objects.PropertyAction

toPropertyAction :: (MonadIO m, IsPropertyAction o) => o -> m PropertyAction

Cast to PropertyAction, for types for which this is known to be safe. For general casts, use castTo.

noPropertyAction :: Maybe PropertyAction

A convenience alias for Nothing :: Maybe PropertyAction.

Methods

new

propertyActionNew

Arguments

:: (HasCallStack, MonadIO m, IsObject a)

=> Text

name: the name of the action to create

-> a

object: the object that has the property to wrap

-> Text

propertyName: the name of the property

-> m PropertyAction

Returns: a new PropertyAction

Creates a Action corresponding to the value of property propertyName on object.

The property must be existent and readable and writable (and not construct-only).

This function takes a reference on object and doesn't release it until the action is destroyed.

Since: 2.38

Properties

enabled

If action is currently enabled.

If the action is disabled then calls to actionActivate and actionChangeState have no effect.

Since: 2.38

getPropertyActionEnabled :: (MonadIO m, IsPropertyAction o) => o -> m Bool

Get the value of the “enabled” property. When overloading is enabled, this is equivalent to

get propertyAction #enabled

invertBoolean

If True, the state of the action will be the negation of the property value, provided the property is boolean.

Since: 2.46

constructPropertyActionInvertBoolean :: IsPropertyAction o => Bool -> IO (GValueConstruct o)

Construct a GValueConstruct with valid value for the “invert-boolean” property. This is rarely needed directly, but it is used by new.

getPropertyActionInvertBoolean :: (MonadIO m, IsPropertyAction o) => o -> m Bool

Get the value of the “invert-boolean” property. When overloading is enabled, this is equivalent to

get propertyAction #invertBoolean

name

The name of the action. This is mostly meaningful for identifying the action once it has been added to a ActionMap.

Since: 2.38

constructPropertyActionName :: IsPropertyAction o => Text -> IO (GValueConstruct o)

Construct a GValueConstruct with valid value for the “name” property. This is rarely needed directly, but it is used by new.

getPropertyActionName :: (MonadIO m, IsPropertyAction o) => o -> m (Maybe Text)

Get the value of the “name” property. When overloading is enabled, this is equivalent to

get propertyAction #name

object

The object to wrap a property on.

The object must be a non-Nothing Object with properties.

Since: 2.38

constructPropertyActionObject :: (IsPropertyAction o, IsObject a) => a -> IO (GValueConstruct o)

Construct a GValueConstruct with valid value for the “object” property. This is rarely needed directly, but it is used by new.

parameterType

The type of the parameter that must be given when activating the action.

Since: 2.38

getPropertyActionParameterType :: (MonadIO m, IsPropertyAction o) => o -> m (Maybe VariantType)

Get the value of the “parameter-type” property. When overloading is enabled, this is equivalent to

get propertyAction #parameterType

propertyName

The name of the property to wrap on the object.

The property must exist on the passed-in object and it must be readable and writable (and not construct-only).

Since: 2.38

constructPropertyActionPropertyName :: IsPropertyAction o => Text -> IO (GValueConstruct o)

Construct a GValueConstruct with valid value for the “property-name” property. This is rarely needed directly, but it is used by new.

state

The state of the action, or Nothing if the action is stateless.

Since: 2.38

getPropertyActionState :: (MonadIO m, IsPropertyAction o) => o -> m (Maybe GVariant)

Get the value of the “state” property. When overloading is enabled, this is equivalent to

get propertyAction #state

stateType

The VariantType of the state that the action has, or Nothing if the action is stateless.

Since: 2.38

getPropertyActionStateType :: (MonadIO m, IsPropertyAction o) => o -> m (Maybe VariantType)

Get the value of the “state-type” property. When overloading is enabled, this is equivalent to

get propertyAction #stateType