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Gio.ActionGroup

interface

GActionGroup represents a group of actions.

Actions can be used to expose functionality in a structured way, either from one part of a program to another, or to the outside world. Action groups are often used together with a MenuModel that provides additional representation data for displaying the actions to the user, e.g. in a menu.

The main way to interact with the actions in a GActionGroup is to activate them with ActionGroup.activate_action. Activating an action may require a GLib.Variant parameter. The required type of the parameter can be inquired with ActionGroup.get_action_parameter_type. Actions may be disabled, see ActionGroup.get_action_enabled. Activating a disabled action has no effect.

Actions may optionally have a state in the form of a GLib.Variant. The current state of an action can be inquired with ActionGroup.get_action_state. Activating a stateful action may change its state, but it is also possible to set the state by calling ActionGroup.change_action_state.

As typical example, consider a text editing application which has an option to change the current font to ‘bold’. A good way to represent this would be a stateful action, with a boolean state. Activating the action would toggle the state.

Each action in the group has a unique name (which is a string). All method calls, except ActionGroup.list_actions take the name of an action as an argument.

The GActionGroup API is meant to be the ‘public’ API to the action group. The calls here are exactly the interaction that ‘external forces’ (eg: UI, incoming D-Bus messages, etc.) are supposed to have with actions. ‘Internal’ APIs (ie: ones meant only to be accessed by the action group implementation) are found on subclasses. This is why you will find – for example – ActionGroup.get_action_enabled but not an equivalent set_action_enabled() method.

Signals are emitted on the action group in response to state changes on individual actions.

Implementations of GActionGroup should provide implementations for the virtual functions ActionGroup.list_actions and ActionGroup.query_action. The other virtual functions should not be implemented — their ‘wrappers’ are actually implemented with calls to ActionGroup.query_action.

Methods

action_added

def action_added(self, action_name: str) -> None

Emits the ActionGroup.action-added signal on action_group.

This function should only be called by ActionGroup implementations.

Parameters:

  • action_name — the name of an action in the group

action_enabled_changed

def action_enabled_changed(self, action_name: str, enabled: bool) -> None

Emits the ActionGroup.action-enabled-changed signal on action_group.

This function should only be called by ActionGroup implementations.

Parameters:

  • action_name — the name of an action in the group
  • enabled — whether the action is now enabled

action_removed

def action_removed(self, action_name: str) -> None

Emits the ActionGroup.action-removed signal on action_group.

This function should only be called by ActionGroup implementations.

Parameters:

  • action_name — the name of an action in the group

action_state_changed

def action_state_changed(self, action_name: str, state: GLib.Variant) -> None

Emits the ActionGroup.action-state-changed signal on action_group.

This function should only be called by ActionGroup implementations.

Parameters:

  • action_name — the name of an action in the group
  • state — the new state of the named action

activate_action

def activate_action(self, action_name: str, parameter: GLib.Variant | None = ...) -> None

Activate the named action within action_group.

If the action is expecting a parameter, then the correct type of parameter must be given as parameter. If the action is expecting no parameters then parameter must be NULL. See ActionGroup.get_action_parameter_type.

If the ActionGroup implementation supports asynchronous remote activation over D-Bus, this call may return before the relevant D-Bus traffic has been sent, or any replies have been received. In order to block on such asynchronous activation calls, DBusConnection.flush should be called prior to the code, which depends on the result of the action activation. Without flushing the D-Bus connection, there is no guarantee that the action would have been activated.

The following code which runs in a remote app instance, shows an example of a ‘quit’ action being activated on the primary app instance over D-Bus. Here DBusConnection.flush is called before exit(). Without g_dbus_connection_flush(), the ‘quit’ action may fail to be activated on the primary instance.

// call ‘quit’ action on primary instance
g_action_group_activate_action (G_ACTION_GROUP (app), "quit", NULL);

// make sure the action is activated now
g_dbus_connection_flush (…);

g_debug ("Application has been terminated. Exiting.");

exit (0);

Parameters:

  • action_name — the name of the action to activate
  • parameter — parameters to the activation

change_action_state

def change_action_state(self, action_name: str, value: GLib.Variant) -> None

Request for the state of the named action within action_group to be changed to value.

The action must be stateful and value must be of the correct type. See ActionGroup.get_action_state_type.

This call merely requests a change. The action may refuse to change its state or may change its state to something other than value. See ActionGroup.get_action_state_hint.

If the value GVariant is floating, it is consumed.

Parameters:

  • action_name — the name of the action to request the change on
  • value — the new state

get_action_enabled

def get_action_enabled(self, action_name: str) -> bool

Checks if the named action within action_group is currently enabled.

An action must be enabled in order to be activated or in order to have its state changed from outside callers.

Parameters:

  • action_name — the name of the action to query

get_action_parameter_type

def get_action_parameter_type(self, action_name: str) -> GLib.VariantType | None

Queries the type of the parameter that must be given when activating the named action within action_group.

When activating the action using ActionGroup.activate_action, the GLib.Variant given to that function must be of the type returned by this function.

In the case that this function returns NULL, you must not give any GLib.Variant, but NULL instead.

The parameter type of a particular action will never change but it is possible for an action to be removed and for a new action to be added with the same name but a different parameter type.

Parameters:

  • action_name — the name of the action to query

get_action_state

def get_action_state(self, action_name: str) -> GLib.Variant | None

Queries the current state of the named action within action_group.

If the action is not stateful then NULL will be returned. If the action is stateful then the type of the return value is the type given by ActionGroup.get_action_state_type.

The return value (if non-NULL) should be freed with GLib.Variant.unref when it is no longer required.

Parameters:

  • action_name — the name of the action to query

get_action_state_hint

def get_action_state_hint(self, action_name: str) -> GLib.Variant | None

Requests a hint about the valid range of values for the state of the named action within action_group.

If NULL is returned it either means that the action is not stateful or that there is no hint about the valid range of values for the state of the action.

If a GLib.Variant array is returned then each item in the array is a possible value for the state. If a GLib.Variant pair (ie: two-tuple) is returned then the tuple specifies the inclusive lower and upper bound of valid values for the state.

In any case, the information is merely a hint. It may be possible to have a state value outside of the hinted range and setting a value within the range may fail.

The return value (if non-NULL) should be freed with GLib.Variant.unref when it is no longer required.

Parameters:

  • action_name — the name of the action to query

get_action_state_type

def get_action_state_type(self, action_name: str) -> GLib.VariantType | None

Queries the type of the state of the named action within action_group.

If the action is stateful then this function returns the GLib.VariantType of the state. All calls to ActionGroup.change_action_state must give a GLib.Variant of this type and ActionGroup.get_action_state will return a GLib.Variant of the same type.

If the action is not stateful then this function will return NULL. In that case, ActionGroup.get_action_state will return NULL and you must not call ActionGroup.change_action_state.

The state type of a particular action will never change but it is possible for an action to be removed and for a new action to be added with the same name but a different state type.

Parameters:

  • action_name — the name of the action to query

has_action

def has_action(self, action_name: str) -> bool

Checks if the named action exists within action_group.

Parameters:

  • action_name — the name of the action to check for

list_actions

def list_actions(self) -> list[str]

Lists the actions contained within action_group.

The caller is responsible for freeing the list with GLib.strfreev when it is no longer required.

query_action

def query_action(self, action_name: str) -> tuple[bool, bool, GLib.VariantType, GLib.VariantType, GLib.Variant, GLib.Variant]

Queries all aspects of the named action within an action_group.

This function acquires the information available from ActionGroup.has_action, ActionGroup.get_action_enabled, ActionGroup.get_action_parameter_type, ActionGroup.get_action_state_type, ActionGroup.get_action_state_hint and ActionGroup.get_action_state with a single function call.

This provides two main benefits.

The first is the improvement in efficiency that comes with not having to perform repeated lookups of the action in order to discover different things about it. The second is that implementing ActionGroup can now be done by only overriding this one virtual function.

The interface provides a default implementation of this function that calls the individual functions, as required, to fetch the information. The interface also provides default implementations of those functions that call this function. All implementations, therefore, must override either this function or all of the others.

If the action exists, TRUE is returned and any of the requested fields (as indicated by having a non-NULL reference passed in) are filled. If the action doesn’t exist, FALSE is returned and the fields may or may not have been modified.

Parameters:

  • action_name — the name of an action in the group

Virtual methods

do_action_added

def do_action_added(self, action_name: str) -> None

Emits the ActionGroup.action-added signal on action_group.

This function should only be called by ActionGroup implementations.

Parameters:

  • action_name — the name of an action in the group

do_action_enabled_changed

def do_action_enabled_changed(self, action_name: str, enabled: bool) -> None

Emits the ActionGroup.action-enabled-changed signal on action_group.

This function should only be called by ActionGroup implementations.

Parameters:

  • action_name — the name of an action in the group
  • enabled — whether the action is now enabled

do_action_removed

def do_action_removed(self, action_name: str) -> None

Emits the ActionGroup.action-removed signal on action_group.

This function should only be called by ActionGroup implementations.

Parameters:

  • action_name — the name of an action in the group

do_action_state_changed

def do_action_state_changed(self, action_name: str, state: GLib.Variant) -> None

Emits the ActionGroup.action-state-changed signal on action_group.

This function should only be called by ActionGroup implementations.

Parameters:

  • action_name — the name of an action in the group
  • state — the new state of the named action

do_activate_action

def do_activate_action(self, action_name: str, parameter: GLib.Variant | None = ...) -> None

Activate the named action within action_group.

If the action is expecting a parameter, then the correct type of parameter must be given as parameter. If the action is expecting no parameters then parameter must be NULL. See ActionGroup.get_action_parameter_type.

If the ActionGroup implementation supports asynchronous remote activation over D-Bus, this call may return before the relevant D-Bus traffic has been sent, or any replies have been received. In order to block on such asynchronous activation calls, DBusConnection.flush should be called prior to the code, which depends on the result of the action activation. Without flushing the D-Bus connection, there is no guarantee that the action would have been activated.

The following code which runs in a remote app instance, shows an example of a ‘quit’ action being activated on the primary app instance over D-Bus. Here DBusConnection.flush is called before exit(). Without g_dbus_connection_flush(), the ‘quit’ action may fail to be activated on the primary instance.

// call ‘quit’ action on primary instance
g_action_group_activate_action (G_ACTION_GROUP (app), "quit", NULL);

// make sure the action is activated now
g_dbus_connection_flush (…);

g_debug ("Application has been terminated. Exiting.");

exit (0);

Parameters:

  • action_name — the name of the action to activate
  • parameter — parameters to the activation

do_change_action_state

def do_change_action_state(self, action_name: str, value: GLib.Variant) -> None

Request for the state of the named action within action_group to be changed to value.

The action must be stateful and value must be of the correct type. See ActionGroup.get_action_state_type.

This call merely requests a change. The action may refuse to change its state or may change its state to something other than value. See ActionGroup.get_action_state_hint.

If the value GVariant is floating, it is consumed.

Parameters:

  • action_name — the name of the action to request the change on
  • value — the new state

do_get_action_enabled

def do_get_action_enabled(self, action_name: str) -> bool

Checks if the named action within action_group is currently enabled.

An action must be enabled in order to be activated or in order to have its state changed from outside callers.

Parameters:

  • action_name — the name of the action to query

do_get_action_parameter_type

def do_get_action_parameter_type(self, action_name: str) -> GLib.VariantType | None

Queries the type of the parameter that must be given when activating the named action within action_group.

When activating the action using ActionGroup.activate_action, the GLib.Variant given to that function must be of the type returned by this function.

In the case that this function returns NULL, you must not give any GLib.Variant, but NULL instead.

The parameter type of a particular action will never change but it is possible for an action to be removed and for a new action to be added with the same name but a different parameter type.

Parameters:

  • action_name — the name of the action to query

do_get_action_state

def do_get_action_state(self, action_name: str) -> GLib.Variant | None

Queries the current state of the named action within action_group.

If the action is not stateful then NULL will be returned. If the action is stateful then the type of the return value is the type given by ActionGroup.get_action_state_type.

The return value (if non-NULL) should be freed with GLib.Variant.unref when it is no longer required.

Parameters:

  • action_name — the name of the action to query

do_get_action_state_hint

def do_get_action_state_hint(self, action_name: str) -> GLib.Variant | None

Requests a hint about the valid range of values for the state of the named action within action_group.

If NULL is returned it either means that the action is not stateful or that there is no hint about the valid range of values for the state of the action.

If a GLib.Variant array is returned then each item in the array is a possible value for the state. If a GLib.Variant pair (ie: two-tuple) is returned then the tuple specifies the inclusive lower and upper bound of valid values for the state.

In any case, the information is merely a hint. It may be possible to have a state value outside of the hinted range and setting a value within the range may fail.

The return value (if non-NULL) should be freed with GLib.Variant.unref when it is no longer required.

Parameters:

  • action_name — the name of the action to query

do_get_action_state_type

def do_get_action_state_type(self, action_name: str) -> GLib.VariantType | None

Queries the type of the state of the named action within action_group.

If the action is stateful then this function returns the GLib.VariantType of the state. All calls to ActionGroup.change_action_state must give a GLib.Variant of this type and ActionGroup.get_action_state will return a GLib.Variant of the same type.

If the action is not stateful then this function will return NULL. In that case, ActionGroup.get_action_state will return NULL and you must not call ActionGroup.change_action_state.

The state type of a particular action will never change but it is possible for an action to be removed and for a new action to be added with the same name but a different state type.

Parameters:

  • action_name — the name of the action to query

do_has_action

def do_has_action(self, action_name: str) -> bool

Checks if the named action exists within action_group.

Parameters:

  • action_name — the name of the action to check for

do_list_actions

def do_list_actions(self) -> list[str]

Lists the actions contained within action_group.

The caller is responsible for freeing the list with GLib.strfreev when it is no longer required.

do_query_action

def do_query_action(self, action_name: str) -> tuple[bool, bool, GLib.VariantType, GLib.VariantType, GLib.Variant, GLib.Variant]

Queries all aspects of the named action within an action_group.

This function acquires the information available from ActionGroup.has_action, ActionGroup.get_action_enabled, ActionGroup.get_action_parameter_type, ActionGroup.get_action_state_type, ActionGroup.get_action_state_hint and ActionGroup.get_action_state with a single function call.

This provides two main benefits.

The first is the improvement in efficiency that comes with not having to perform repeated lookups of the action in order to discover different things about it. The second is that implementing ActionGroup can now be done by only overriding this one virtual function.

The interface provides a default implementation of this function that calls the individual functions, as required, to fetch the information. The interface also provides default implementations of those functions that call this function. All implementations, therefore, must override either this function or all of the others.

If the action exists, TRUE is returned and any of the requested fields (as indicated by having a non-NULL reference passed in) are filled. If the action doesn’t exist, FALSE is returned and the fields may or may not have been modified.

Parameters:

  • action_name — the name of an action in the group

Signals

action-added

def on_action_added(self, action_name: str) -> None: ...

Signals that a new action was just added to the group.

This signal is emitted after the action has been added and is now visible.

action-enabled-changed

def on_action_enabled_changed(self, action_name: str, enabled: bool) -> None: ...

Signals that the enabled status of the named action has changed.

action-removed

def on_action_removed(self, action_name: str) -> None: ...

Signals that an action is just about to be removed from the group.

This signal is emitted before the action is removed, so the action is still visible and can be queried from the signal handler.

action-state-changed

def on_action_state_changed(self, action_name: str, value: GLib.Variant) -> None: ...

Signals that the state of the named action has changed.