gio:action, gobject:object, common-lisp:standard-object, common-lisp:t

None

The g:property-action class is a way to get a g:action object with a state value reflecting and controlling the value of a g: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 g:param-spec instance.

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 enumeration then the state will be string-typed and conversion will automatically be performed between the enumeration value and "nick" string.

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 g:variant parameter 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. The g:property-action object 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 g:action object corresponding to the visible-child-name property of a gtk:stack widget 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 gtk:stack widget.

An anti-example would be to bind to the visible-child-name property of a gtk:stack widget if this value is actually stored in GSettings. In that case, the real source of the value is GSettings. If you want a g:action object to control a setting stored in GSettings, see the g_settings_create_action() function instead, and possibly combine its use with the g_settings_bind() function.