## BonoboObject

BonoboObject — Base object for wrapping Bonobo::Unknown derived objects.

## Synopsis

    #define     BONOBO_OBJECT_TYPE
    #define     BONOBO_OBJREF                   (o)
    void        (*BonoboObjectPOAFn)            (PortableServer_Servant servant,
                                                 CORBA_Environment *ev);
    struct      BonoboObjectPrivate;
    typedef     BonoboObjectHeader;
    #define     BONOBO_OBJECT_HEADER_SIZE
    #define     BONOBO_OBJECT_SIGNATURE
    #define     BONOBO_SERVANT_SIGNATURE
    typedef     BonoboObject;
    typedef     BonoboObjectClass;
    void        bonobo_object_add_interface     (BonoboObject *object,
                                                 BonoboObject *newobj);
    BonoboObject* bonobo_object_query_local_interface
                                                (BonoboObject *object,
                                                 const char *repo_id);
    Bonobo_Unknown bonobo_object_query_interface
                                                (BonoboObject *object,
                                                 const char *repo_id,
                                                 CORBA_Environment *opt_ev);
    Bonobo_Unknown bonobo_object_corba_objref   (BonoboObject *object);
    Bonobo_Unknown bonobo_object_dup_ref        (Bonobo_Unknown object,
                                                 CORBA_Environment *opt_ev);
    Bonobo_Unknown bonobo_object_release_unref  (Bonobo_Unknown object,
                                                 CORBA_Environment *opt_ev);
    gpointer    bonobo_object_ref               (gpointer obj);
    void        bonobo_object_idle_unref        (gpointer obj);
    gpointer    bonobo_object_unref             (gpointer obj);
    void        bonobo_object_set_immortal      (BonoboObject *object,
                                                 gboolean immortal);
    gpointer    bonobo_object_trace_refs        (gpointer obj,
                                                 const char *fn,
                                                 int line,
                                                 gboolean ref);
    void        bonobo_object_dump_interfaces   (BonoboObject *object);
    void        bonobo_object_check_env         (BonoboObject *object,
                                                 CORBA_Object corba_object,
                                                 CORBA_Environment *ev);
    #define     BONOBO_OBJECT_CHECK             (o,c,e)
    gboolean    bonobo_unknown_ping             (Bonobo_Unknown object,
                                                 CORBA_Environment *opt_ev);
    void        bonobo_object_list_unref_all    (GList **list);
    void        bonobo_object_slist_unref_all   (GSList **list);
    BonoboObject* bonobo_object                 (gpointer p);
    #define     bonobo_object_fast              (o)
    #define     bonobo_object_from_servant      (s)
    #define     bonobo_object_get_servant       (o)
    GType       bonobo_type_unique              (GType parent_type,
                                                 BonoboObjectPOAFn init_fn,
                                                 BonoboObjectPOAFn fini_fn,
                                                 int epv_struct_offset,
                                                 const GTypeInfo *info,
                                                 const gchar *type_name);
    gboolean    bonobo_type_setup               (GType type,
                                                 BonoboObjectPOAFn init_fn,
                                                 BonoboObjectPOAFn fini_fn,
                                                 int epv_struct_offset);
    #define     BONOBO_TYPE_FUNC_FULL           (class_name, corba_name, parent, prefix)
    #define     BONOBO_TYPE_FUNC                (class_name, parent, prefix)

## Description

BonoboObject provides an easy to use way of writing CORBA servers. It drastically simplifies the issues of epv and vepv construction by automating these, and automatically instantiates a CORBA_Object on g_object_new. This removes clutter from construction time. For libbonobo-2.0, it strongly deprecates BonoboXObject.

Again if you are looking to implement a CORBA interface you want to see BonoboXObject.

The `Bonobo::Unknown` interface (wrapped by BonoboObject) is the foundation for the component system: it provides life cycle management for objects as well as service discovery.

The Bonobo interfaces are all based on the `Bonobo::Unknown` interface. This interface is very simple and provides two basic services: object lifetime management and object functionality-discovery. This interface only contains three methods, here it is:

      module Bonobo {
          interface Unknown {
              void void ref();
              void void unref();
              Object query_interface (in string repoid);
          };
      };

The `ref()` and `unref()` methods are used to control the lifetime of an object. The `query_interface` method is used to discover optional functionality provided by the object implementation.

The lifetime management is based on reference counting: when a component is initially launched, it starts life with a reference count of one. This reference is held by the component invoker. Each time a reference is kept to this object (say, you store a copy of the object in an array), the reference count is incremented. Every time a reference goes out of scope, the reference count needs to be decremented. When the reference count reaches zero, the component knows that there are no outstanding references to it, and it is safe to shutdown. At this point, the component shuts down.

It is possible to ask an object which implements the `Bonobo::Unknown` interface if it supports other CORBA interfaces. For example, it would be possible to ask an object whether it supports the "IDL:Bonobo/EmbeddablePrint:1.0" interface to find out if it is possible to print its contents. If the return value from invoking the `query_interface` method on the interface is CORBA_OBJECT_NIL, then we know that the requested interface is not supported. Otherwise, we can invoke IDL:Bonobo/EmbeddablePrint:1.0 methods on the returned CORBA Object.

Clients of the `query_interface` method use it to discover dynamically if a component supports a given interface. Sometimes the client code would require a specific interface to exist, but many times it is possible to operate in a "downgraded" mode. You should design your code to be able to cope with the lack of interfaces in objects. This will allow your program to deal with more components, and this also allows components to work in more situations.

For example, a help browser can load an HTML renderer component and ask this component which sort of features are supported by it:

    stop_animations (BrowserHTML html)
    {
      BrowserControl control

      control = html->query_interface ("IDL:Browser/Control:1.0");
      if (control)
              control->stop_animations();
    }

The return value of the query_interface invocation contains a reference to a CORBA object that is derived from the `Bonobo::Unknown` interface or CORBA_OBJECT_NIL if the interface is not supported by the object. And this interface would have been already `ref()`ed before it was returned. It is up to the caller to call `unref()` when they are done using the interface.

BonoboObject implements the Bonobo::Unknown interface and exports the implementations of the methods in this class to simplify creating new objects that inherit from Bonobo::Unknown. This base object provides default implementations for the ref, unref and query_interface methods.

Other implementations reuse this implementation by listing on their VEPV tables the bonobo_object_epv entry point vector.

The `Bonobo::Unknown` interface is inspired by the Microsoft COM `IUnknown` interface but it has been translated into the CORBA world.

## Details

### BONOBO_OBJECT_TYPE

    #define BONOBO_OBJECT_TYPE        BONOBO_TYPE_OBJECT /* deprecated, you should use BONOBO_TYPE_OBJECT */

Returns the GtkType for the BonoboObject object.

### BONOBO_OBJREF()

    #define BONOBO_OBJREF(o)          (bonobo_object_corba_objref(BONOBO_OBJECT(o)))

`o` : |

### BonoboObjectPOAFn ()

    void        (*BonoboObjectPOAFn)            (PortableServer_Servant servant,
                                                 CORBA_Environment *ev);

`servant` : |
`ev` : |

### struct BonoboObjectPrivate

    struct BonoboObjectPrivate;

Private information kept by the BonoboObject. This should not be used by BonoboObject users.

### BonoboObjectHeader

    typedef struct {
    	GObject              base;             /* pointer + guint + pointer */
    	BonoboObjectPrivate *priv;             /* pointer */
    	guint                object_signature; /* guint   */
    } BonoboObjectHeader;

### BONOBO_OBJECT_HEADER_SIZE

    #define BONOBO_OBJECT_HEADER_SIZE (sizeof (BonoboObjectHeader))

### BONOBO_OBJECT_SIGNATURE

    #define BONOBO_OBJECT_SIGNATURE   0xaef2

### BONOBO_SERVANT_SIGNATURE

    #define BONOBO_SERVANT_SIGNATURE  0x2fae

### BonoboObject

    typedef struct {
    	/* A GObject and its signature of type BonoboObjectHeader */
    	GObject              base;             /* pointer + guint + pointer */
    	BonoboObjectPrivate *priv;             /* pointer */
    	guint                object_signature; /* guint   */

    	/* A Servant and its signature - same memory layout */
    	POA_Bonobo_Unknown   servant;          /* pointer + pointer */
    	guint                dummy;            /* guint   */
    	Bonobo_Unknown       corba_objref;     /* pointer */
    	guint                servant_signature;
    } BonoboObject;

### BonoboObjectClass

    typedef struct {
    	GObjectClass parent_class;

    	/* signals. */
    	void         (*destroy)          (BonoboObject *object);
    	void         (*system_exception) (BonoboObject *object,
    					  CORBA_Object  cobject,
    					  CORBA_Environment *ev);

    	BonoboObjectPOAFn          poa_init_fn;
    	BonoboObjectPOAFn          poa_fini_fn;

    	POA_Bonobo_Unknown__vepv       *vepv;

    	/* The offset of this class' additional epv */
    	int                             epv_struct_offset;

    	PortableServer_ServantBase__epv base_epv;
    	POA_Bonobo_Unknown__epv         epv;

    	gpointer                        dummy[4];
    } BonoboObjectClass;

### bonobo_object_add_interface ()

    void        bonobo_object_add_interface     (BonoboObject *object,
                                                 BonoboObject *newobj);

Adds the interfaces supported by `newobj` to the list of interfaces for `object`. This function adds the interfaces supported by `newobj` to the list of interfaces support by `object`. It should never be used when the object has been exposed to the world. This is a firm part of the contract.

`object` : | The BonoboObject to which an interface is going to be added.
`newobj` : | The BonoboObject containing the new interface to be added.

### bonobo_object_query_local_interface ()

    BonoboObject* bonobo_object_query_local_interface
                                                (BonoboObject *object,
                                                 const char *repo_id);

`object` : | A BonoboObject which is the aggregate of multiple objects.
`repo_id` : | The id of the interface being queried.
Returns : | A BonoboObject for the requested interface.

### bonobo_object_query_interface ()

    Bonobo_Unknown bonobo_object_query_interface
                                                (BonoboObject *object,
                                                 const char *repo_id,
                                                 CORBA_Environment *opt_ev);

`object` : | A BonoboObject to be queried for a given interface.
`repo_id` : | The name of the interface to be queried.
`opt_ev` : | optional exception environment
Returns : | The CORBA interface named `repo_id` for `object`.

### bonobo_object_corba_objref ()

    Bonobo_Unknown bonobo_object_corba_objref   (BonoboObject *object);

`object` : | A BonoboObject whose CORBA object is requested.
Returns : | The CORBA interface object for which `object` is a wrapper.

### bonobo_object_dup_ref ()

    Bonobo_Unknown bonobo_object_dup_ref        (Bonobo_Unknown object,
                                                 CORBA_Environment *opt_ev);

This function returns a duplicated CORBA Object reference; it also bumps the ref count on the object. This is ideal to use in any method returning a Bonobo_Object in a CORBA impl. If object is CORBA_OBJECT_NIL it is returned unaffected.

`object` : | a Bonobo_Unknown corba object
`opt_ev` : | an optional exception environment
Returns : | duplicated & ref'd corba object reference.

### bonobo_object_release_unref ()

    Bonobo_Unknown bonobo_object_release_unref  (Bonobo_Unknown object,
                                                 CORBA_Environment *opt_ev);

This function releases a CORBA Object reference; it also decrements the ref count on the bonobo object. This is the converse of bonobo_object_dup_ref. We tolerate object == CORBA_OBJECT_NIL silently.

`object` : | a Bonobo_Unknown corba object
`opt_ev` : | an optional exception environment
Returns : |

### bonobo_object_ref ()

    gpointer    bonobo_object_ref               (gpointer obj);

Increments the reference count for the aggregate BonoboObject.

`obj` : |
Returns : |

### bonobo_object_idle_unref ()

    void        bonobo_object_idle_unref        (gpointer obj);

`obj` : |

### bonobo_object_unref ()

    gpointer    bonobo_object_unref             (gpointer obj);

Decrements the reference count for the aggregate BonoboObject.

`obj` : |
Returns : |

### bonobo_object_set_immortal ()

    void        bonobo_object_set_immortal      (BonoboObject *object,
                                                 gboolean immortal);

`object` : |
`immortal` : |

### bonobo_object_trace_refs ()

    gpointer    bonobo_object_trace_refs        (gpointer obj,
                                                 const char *fn,
                                                 int line,
                                                 gboolean ref);

`obj` : |
`fn` : |
`line` : |
`ref` : |
Returns : |

### bonobo_object_dump_interfaces ()

    void        bonobo_object_dump_interfaces   (BonoboObject *object);

`object` : |

### bonobo_object_check_env ()

    void        bonobo_object_check_env         (BonoboObject *object,
                                                 CORBA_Object corba_object,
                                                 CORBA_Environment *ev);

This routine verifies the `ev` environment for any fatal system exceptions. If a system exception occurs, the object raises a "system_exception" signal. The idea is that GObjects which are used to wrap a CORBA interface can use this function to notify the user if a fatal exception has occurred, causing the object to become defunct.

`object` : | The object on which we operate
`corba_object` : |
`ev` : | CORBA Environment to check

### BONOBO_OBJECT_CHECK()

    #define     BONOBO_OBJECT_CHECK(o,c,e)

Checks if the exception in `e` needs to be signaled. If so, then the proper exception signal is generated on the BonoboObject object `o` for the CORBA reference `c`.

`o` : |
`c` : |
`e` : |

### bonobo_unknown_ping ()

    gboolean    bonobo_unknown_ping             (Bonobo_Unknown object,
                                                 CORBA_Environment *opt_ev);

Pings the object `object` using the ref/unref methods from Bonobo::Unknown. You can use this one to see if a remote object has gone away.

`object` : | a CORBA object reference of type Bonobo::Unknown
`opt_ev` : | optional exception environment
Returns : | `TRUE` if the Bonobo::Unknown `object` is alive.

### bonobo_object_list_unref_all ()

    void        bonobo_object_list_unref_all    (GList **list);

This routine unrefs all valid objects in the list and then removes them from `list` if they have not already been so removed.

`list` : | A list of BonoboObjects *s

### bonobo_object_slist_unref_all ()

    void        bonobo_object_slist_unref_all   (GSList **list);

`list` : |

### bonobo_object ()

    BonoboObject* bonobo_object                 (gpointer p);

This function can be passed a BonoboObject * or a PortableServer_Servant, and it will return a BonoboObject *.

`p` : | a pointer to something
Returns : | a BonoboObject or NULL on error.

### bonobo_object_fast()

    #define     bonobo_object_fast(o)

`o` : |

### bonobo_object_from_servant()

    #define       bonobo_object_from_servant(s) ((BonoboObject *)(((guchar *) (s)) - BONOBO_OBJECT_HEADER_SIZE))

`s` : |
Returns : |

### bonobo_object_get_servant()

    #define       bonobo_object_get_servant(o)  ((PortableServer_Servant)((guchar *)(o) + BONOBO_OBJECT_HEADER_SIZE))

`o` : |
Returns : |

### bonobo_type_unique ()

    GType       bonobo_type_unique              (GType parent_type,
                                                 BonoboObjectPOAFn init_fn,
                                                 BonoboObjectPOAFn fini_fn,
                                                 int epv_struct_offset,
                                                 const GTypeInfo *info,
                                                 const gchar *type_name);

This function is the main entry point for deriving bonobo server interfaces.

`parent_type` : | the parent GType
`init_fn` : | a POA initialization function
`fini_fn` : | a POA finialization function or NULL
`epv_struct_offset` : | the offset into the struct that the epv commences at, or 0 if we are inheriting a plain GObject from a BonoboObject, adding no new CORBA interfaces
`info` : | the standard GTypeInfo.
`type_name` : |
Returns : | the constructed GType.

### bonobo_type_setup ()

    gboolean    bonobo_type_setup               (GType type,
                                                 BonoboObjectPOAFn init_fn,
                                                 BonoboObjectPOAFn fini_fn,
                                                 int epv_struct_offset);

This function initializes a type derived from BonoboObject, such that when you instantiate a new object of this type with g_type_new the CORBA object will be correctly created and embedded.

`type` : | The type to initialize
`init_fn` : | the POA_init function for the CORBA interface or NULL
`fini_fn` : | NULL or a custom POA free fn.
`epv_struct_offset` : | the offset in the class structure where the epv is or 0
Returns : | TRUE on success, FALSE on error.

### BONOBO_TYPE_FUNC_FULL()

    #define     BONOBO_TYPE_FUNC_FULL(class_name, corba_name, parent, prefix)

`class_name` : |
`corba_name` : |
`parent` : |
`prefix` : |

### BONOBO_TYPE_FUNC()

    #define     BONOBO_TYPE_FUNC(class_name, parent, prefix)

`class_name` : |
`parent` : |
`prefix` : |

## See Also

GObject