## MateComponentPropertyBag MateComponentPropertyBag — Implements a generic property storage interface |

## Synopsis

                        MateComponentPropertyBagClass;
                        MateComponentPropertyBag;
    #define             MATECOMPONENT_PROPERTY_READABLE
    #define             MATECOMPONENT_PROPERTY_WRITEABLE
    #define             MATECOMPONENT_PROPERTY_WRITABLE
    #define             MATECOMPONENT_PROPERTY_NO_LISTENING
    #define             MATECOMPONENT_PROPERTY_NO_AUTONOTIFY
                        MateComponentProperty;
    void                (*MateComponentPropertyGetFn)              (MateComponentPropertyBag *bag,
                                                             MateComponentArg *arg,
                                                             guint arg_id,
                                                             CORBA_Environment *ev,
                                                             gpointer user_data);
    void                (*MateComponentPropertySetFn)              (MateComponentPropertyBag *bag,
                                                             const MateComponentArg *arg,
                                                             guint arg_id,
                                                             CORBA_Environment *ev,
                                                             gpointer user_data);
    MateComponentPropertyBag * matecomponent_property_bag_new             (MateComponentPropertyGetFn get_prop_cb,
                                                             MateComponentPropertySetFn set_prop_cb,
                                                             gpointer user_data);
    MateComponentPropertyBag * matecomponent_property_bag_new_closure     (GClosure *get_prop,
                                                             GClosure *set_prop);
    MateComponentPropertyBag * matecomponent_property_bag_new_full        (GClosure *get_prop,
                                                             GClosure *set_prop,
                                                             MateComponentEventSource *es);
    MateComponentPropertyBag * matecomponent_property_bag_construct       (MateComponentPropertyBag *pb,
                                                             GClosure *get_prop,
                                                             GClosure *set_prop,
                                                             MateComponentEventSource *es);
    void                matecomponent_property_bag_add             (MateComponentPropertyBag *pb,
                                                             const char *name,
                                                             int idx,
                                                             MateComponentArgType type,
                                                             MateComponentArg *default_value,
                                                             const char *doctitle,
                                                             MateComponent_PropertyFlags flags);
    void                matecomponent_property_bag_add_full        (MateComponentPropertyBag *pb,
                                                             const char *name,
                                                             int idx,
                                                             MateComponentArgType type,
                                                             MateComponentArg *default_value,
                                                             const char *doctitle,
                                                             const char *docstring,
                                                             MateComponent_PropertyFlags flags,
                                                             GClosure *get_prop,
                                                             GClosure *set_prop);
    void                matecomponent_property_bag_remove          (MateComponentPropertyBag *pb,
                                                             const char *name);
    void                matecomponent_property_bag_map_params      (MateComponentPropertyBag *pb,
                                                             GObject *on_instance,
                                                             const GParamSpec **pspecs,
                                                             guint n_params);
    GList *             matecomponent_property_bag_get_prop_list   (MateComponentPropertyBag *pb);

## Description

The PropertyBag is used for many things, particularly for the customization of controls. The important thing to remember about the MateComponentPropertyBag implementation is that no live data is stored in the bag. ie. the Model for the properties is your code.

Consequently when someone requests a properties value, or sets a property the callbacks you supply at bag construction time are called, and the code therein must supply the property. Similarly, when a property changes value inside your object you need to notify the property bag's listeners that it has changed with a call to `matecomponent_event_source_notify_listeners_full`.

Here is a simple example use of the property bag:

Example 11. PropertyBag Callbacks

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    enum {
        PROP_RUNNING,
        PROP_COLOUR
    } MyArgs;
    static void
    get_prop (MateComponentPropertyBag *bag,
          MateComponentArg         *arg,
          guint              arg_id,
          CORBA_Environment *ev,
          gpointer           user_data)
    {
        GtkObject *clock = user_data;
        switch (arg_id) {
        case PROP_RUNNING:
            MATECOMPONENT_ARG_SET_BOOLEAN (arg, clock->is_running);
            break;
        case PROP_COLOUR:
            MATECOMPONENT_ARG_SET_STRING (arg, clock->color);
            break;
        default:
            matecomponent_exception_set (ev, ex_MateComponent_PropertyBag_NotFound);
            break;
        }
    }
    static void
    set_prop (MateComponentPropertyBag *bag,
          const MateComponentArg   *arg,
          guint              arg_id,
          CORBA_Environment *ev,
          gpointer           user_data)
    {
        GtkClock *clock = user_data;
        switch (arg_id) {
        case PROP_RUNNING: {
            guint i = MATECOMPONENT_ARG_GET_BOOLEAN (arg);
            if (i)
                gtk_clock_start (clock);
            else
                gtk_clock_stop (clock);
            break;
        }
        case PROP_COLOUR:
            gtk_clock_set_color (clock, MATECOMPONENT_ARG_GET_STRING (arg));
        default:
            matecomponent_exception_set (ev, ex_MateComponent_PropertyBag_NotFound);
            break;
        }
    }

Then to instantiate the property bag interface and associate it with a control perhaps we do:

Example 12. Adding a PropertyBag to a control

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    MateComponentPropertyBag *pb;
    pb = matecomponent_property_bag_new (get_prop, set_prop, clock);
    matecomponent_control_set_properties (control, pb);
    matecomponent_property_bag_add (pb, "running", PROP_RUNNING,
                 MATECOMPONENT_ARG_BOOLEAN, NULL,
                 _("Whether or not the clock is running"),
                 0);
    matecomponent_property_bag_add (pb, "colour", PROP_COLOUR,
                 MATECOMPONENT_ARG_STRING, NULL,
                 _("The colour of the clock face"),
                 0);
    matecomponent_object_unref (MATECOMPONENT_OBJECT (pb));

And finally we need to notify listeners of changes in various properties so we could perhaps do:

Example 13. Notifying proterty bag listeners

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    static void
    signal_handler (GtkClock *clock, MateComponentPropertyBag *pb)
    {
        MateComponentArg *arg = matecomponent_arg_new (TC_string);
        MATECOMPONENT_ARG_SET_STRING (arg, gtk_clock_get_color (clock));
        matecomponent_event_source_notify_listeners_full (pb->es,
                                   "MateComponent/Property",
                                   "change",
                               "colour",
                                   arg, NULL);
        matecomponent_arg_release (arg);
    }
    ...
        gtk_signal_connect (GTK_OBJECT (clock), "color_changed",
                    GTK_SIGNAL_FUNC (signal_handler), pb);

See also MateComponentArg.

## Details

### MateComponentPropertyBagClass

    typedef struct {
    	MateComponentObjectClass        parent;

    	POA_MateComponent_PropertyBag__epv epv;
    } MateComponentPropertyBagClass;

### MateComponentPropertyBag

    typedef struct {
    	MateComponentObject             parent;
    	MateComponentPropertyBagPrivate *priv;
    	MateComponentEventSource        *es;
    } MateComponentPropertyBag;

### MATECOMPONENT_PROPERTY_READABLE

    #define MATECOMPONENT_PROPERTY_READABLE      MateComponent_PROPERTY_READABLE

If this flag is set, the property allows consulting its value.

### MATECOMPONENT_PROPERTY_WRITEABLE

    #define MATECOMPONENT_PROPERTY_WRITEABLE     MateComponent_PROPERTY_WRITEABLE

If this flag is set, the property supports modification of its value.

### MATECOMPONENT_PROPERTY_WRITABLE

    #define MATECOMPONENT_PROPERTY_WRITABLE      MateComponent_PROPERTY_WRITEABLE

Misspelling of MATECOMPONENT_PROPERTY_WRITEABLE.

### MATECOMPONENT_PROPERTY_NO_LISTENING

    #define MATECOMPONENT_PROPERTY_NO_LISTENING  MateComponent_PROPERTY_NO_LISTENING

If this flag set, when the property changes its value its listeners will *not* be notified.

### MATECOMPONENT_PROPERTY_NO_AUTONOTIFY

    #define MATECOMPONENT_PROPERTY_NO_AUTONOTIFY MateComponent_PROPERTY_NO_AUTONOTIFY

If this flag set, when the property changes its value its listeners will *not* be notified.

### MateComponentProperty

    typedef struct {
    	char		      *name;
    	int                    idx;
    	MateComponentArgType          type;
    	MateComponentArg             *default_value;
    	char		      *doctitle;
    	char		      *docstring;
    	MateComponent_PropertyFlags   flags;

    	MateComponentPropertyPrivate *priv;
    } MateComponentProperty;

Structure that holds information about a property in a MateComponentPropertyBag.

char *`name`; | the canonic name of the property
int `idx`; | unique numeric identifier of the property within the property bag
MateComponentArgType `type`; | type of value contained by this property
MateComponentArg *`default_value`; | the default value
char *`doctitle`; | documentation string title
char *`docstring`; | documentation string
MateComponent_PropertyFlags `flags`; | property flags (read/write, etc.)
MateComponentPropertyPrivate *`priv`; | implementation private data

### MateComponentPropertyGetFn ()

    void                (*MateComponentPropertyGetFn)              (MateComponentPropertyBag *bag,
                                                             MateComponentArg *arg,
                                                             guint arg_id,
                                                             CORBA_Environment *ev,
                                                             gpointer user_data);

Property getter function.

`bag` : | the property bag
`arg` : | output parameter; the caller must place here the property value
`arg_id` : | unique numeric identifier of the property within the property bag
`ev` : | the relevant CORBA environment
`user_data` : | user data

### MateComponentPropertySetFn ()

    void                (*MateComponentPropertySetFn)              (MateComponentPropertyBag *bag,
                                                             const MateComponentArg *arg,
                                                             guint arg_id,
                                                             CORBA_Environment *ev,
                                                             gpointer user_data);

Property setter function.

`bag` : | the property bag
`arg` : | the new property value to be set
`arg_id` : | unique numeric identifier of the property within the property bag
`ev` : | the relevant CORBA environment
`user_data` : | user data

### matecomponent_property_bag_new ()

    MateComponentPropertyBag * matecomponent_property_bag_new             (MateComponentPropertyGetFn get_prop_cb,
                                                             MateComponentPropertySetFn set_prop_cb,
                                                             gpointer user_data);

Creates a new property bag with the specified callbacks.

`get_prop_cb` : | the property get callback
`set_prop_cb` : | the property set callback
`user_data` : | user data for the callbacks
Returns : | A new MateComponentPropertyBag object.

### matecomponent_property_bag_new_closure ()

    MateComponentPropertyBag * matecomponent_property_bag_new_closure     (GClosure *get_prop,
                                                             GClosure *set_prop);

Creates a new property bag with the specified callbacks.

`get_prop` : | the property get closure
`set_prop` : | the property set closure
Returns : | A new MateComponentPropertyBag object.

### matecomponent_property_bag_new_full ()

    MateComponentPropertyBag * matecomponent_property_bag_new_full        (GClosure *get_prop,
                                                             GClosure *set_prop,
                                                             MateComponentEventSource *es);

Creates a new property bag with the specified callbacks.

`get_prop` : | the property get closure
`set_prop` : | the property set closure
`es` : | an event source to aggregate
Returns : | A new MateComponentPropertyBag object.

### matecomponent_property_bag_construct ()

    MateComponentPropertyBag * matecomponent_property_bag_construct       (MateComponentPropertyBag *pb,
                                                             GClosure *get_prop,
                                                             GClosure *set_prop,
                                                             MateComponentEventSource *es);

Constructor, only for use in wrappers and object derivation, please refer to the matecomponent_property_bag_new for normal use.

This function returns `pb`, or `NULL` in case of error. If it returns `NULL`, the passed in `pb` is unrefed.

`pb` : | MateComponentPropertyBag to construct
`get_prop` : | the property get closure
`set_prop` : | the property set closure
`es` : | an event source to aggregate
Returns : | MateComponentPropertyBag pointer or `NULL`.

### matecomponent_property_bag_add ()

    void                matecomponent_property_bag_add             (MateComponentPropertyBag *pb,
                                                             const char *name,
                                                             int idx,
                                                             MateComponentArgType type,
                                                             MateComponentArg *default_value,
                                                             const char *doctitle,
                                                             MateComponent_PropertyFlags flags);

Adds a property to the property bag.

`pb` : | property bag to add to
`name` : | name of new property
`idx` : | integer index for fast callback switch statement
`type` : | the CORBA type eg. TC_long
`default_value` : | the default value or NULL
`doctitle` : | the translated documentation string
`flags` : | various flags

### matecomponent_property_bag_add_full ()

    void                matecomponent_property_bag_add_full        (MateComponentPropertyBag *pb,
                                                             const char *name,
                                                             int idx,
                                                             MateComponentArgType type,
                                                             MateComponentArg *default_value,
                                                             const char *doctitle,
                                                             const char *docstring,
                                                             MateComponent_PropertyFlags flags,
                                                             GClosure *get_prop,
                                                             GClosure *set_prop);

This adds a property to `pb` at the full tilt of complexity.

`pb` : | property bag to add to
`name` : | name of new property
`idx` : | integer index for fast callback switch statement
`type` : | the CORBA type eg. TC_long
`default_value` : | the default value or NULL
`doctitle` : | the translated documentation title
`docstring` : | the translated documentation string
`flags` : | various flags
`get_prop` : | a per property get callback
`set_prop` : | a per property set callback

### matecomponent_property_bag_remove ()

    void                matecomponent_property_bag_remove          (MateComponentPropertyBag *pb,
                                                             const char *name);

removes the property with `name` from `b`.

`pb` : | the property bag
`name` : | name of property to remove.

### matecomponent_property_bag_map_params ()

    void                matecomponent_property_bag_map_params      (MateComponentPropertyBag *pb,
                                                             GObject *on_instance,
                                                             const GParamSpec **pspecs,
                                                             guint n_params);

`pb` : |
`on_instance` : |
`pspecs` : |
`n_params` : |

### matecomponent_property_bag_get_prop_list ()

    GList *             matecomponent_property_bag_get_prop_list   (MateComponentPropertyBag *pb);

`pb` : | A MateComponentPropertyBag.
Returns : | a GList of MateComponentProperty structures. This function is private and should only be used internally, or in a PropertyBag persistence implementation. You should not touch the MateComponentProperty structure unless you know what you're doing.