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SYNOPSIS

#include <agar/core.h>

DESCRIPTION

The Agar object system provides object-oriented programming capabilities including inheritance and virtual functions, as well as high-level features such as serialization, timers, VFS and abstracted data types. It is implemented in C and provides bindings to other languages.

Agar objects can be organized into a tree or virtual filesystem (VFS). Any AG_Object can become the root of a VFS. A VFS can be made persistent to the degree required by the application. Object data is serialized to a machine-independent binary format (using AG_DataSource(3) calls in their load() and save() operations). While an object's metadata (including the name field) must always remain in memory, class-specific data can be serialized to storage and deserialized on demand. Examples include:

Agar GUI's AG_Window(3) is a VFS of AG_Widget(3) instances.
FreeSG (http://freesg.org/)'s scene graph SG(3) is a VFS of SG_Node(3). Non-visible nodes can be paged out, saving memory.
Edacious (http://edacious.org/) represents circuits, components and simulation data using an in-memory VFS. Circuits are saved to a flat binary file which embeds the circuit's serialized data with that of its sub-components (which may include third-party components, in which case AG_Object will autoload any required DSOs).

INITIALIZATION

AG_Object * AG_ObjectNew (AG_Object *parent, const char *name, AG_ObjectClass *classInfo)

void AG_ObjectInit (AG_Object *obj, AG_ObjectClass *classInfo)

void AG_ObjectInitStatic (AG_Object *obj, AG_ObjectClass *classInfo)

void AG_ObjectInitNamed (AG_Object *obj, AG_ObjectClass *classInfo, const char *name)

void AG_ObjectAttach (AG_Object *new_parent, AG_Object *obj)

void AG_ObjectAttachToNamed (AG_Object *vfsRoot, const char *path, AG_Object *child)

void AG_ObjectDetach (AG_Object *obj)

void AG_ObjectMoveToHead (AG_Object *obj)

void AG_ObjectMoveToTail (AG_Object *obj)

void AG_ObjectMoveUp (AG_Object *obj)

void AG_ObjectMoveDown (AG_Object *obj)

void AG_ObjectDelete (AG_Object *obj)

AG_Object * AG_ObjectRoot (AG_Object *obj)

AG_Object * AG_ObjectParent (AG_Object *obj)

AG_Object * AG_ObjectFind (AG_Object *vfsRoot, const char *format, ...)

AG_Object * AG_ObjectFindS (AG_Object *vfsRoot, const char *name)

AG_Object * AG_ObjectFindParent (AG_Object *obj, const char *name, const char *type)

AG_Object * AG_ObjectFindChild (AG_Object *obj, const char *name)

char * AG_ObjectGetName (AG_Object *obj)

int AG_ObjectCopyName (AG_Object *obj, char *pathbuf, size_t pathbuf_len)

void AG_ObjectLock (AG_Object *obj)

void AG_ObjectUnlock (AG_Object *obj)

void AG_LockVFS (AG_Object *obj)

void AG_UnlockVFS (AG_Object *obj)

void AG_ObjectSetName (AG_Object *obj, const char *fmt, ...)

void AG_ObjectSetNameS (AG_Object *obj, const char *name)

void AG_ObjectGenName (AG_Object *obj, AG_ObjectClass *classInfo, char *name, size_t len)

void AG_ObjectGenNamePfx (AG_Object *obj, const char *prefix, char *name, size_t len)

void AG_ObjectSetAttachFn (AG_Object *obj, void (*fn)(struct ag_event *), const char *fmt, ...)

void AG_ObjectSetDetachFn (AG_Object *obj, void (*fn)(struct ag_event *), const char *fmt, ...)

AGOBJECT_FOREACH_CHILD (AG_Object *child, AG_Object *parent, TYPE type)

The AG_ObjectNew() function allocates and initializes a new object instance of the given class. The object is attached to parent, unless the argument is NULL. If name is NULL, a unique name of the form <class-name> #<number> is automatically generated. If both parent and name are specified and the parent object already has a child of the given name, AG_ObjectNew() fails and returns NULL.

The AG_ObjectInit() function initializes an object of the specified class. This involves invoking the init() operation associated with every class in the inheritance hierarchy The name argument specifies a name for the object instance relative to its parent (maximum AG_OBJECT_NAME_MAX bytes and must not contain " / " characters). classInfo should point to an initialized AG_ObjectClass structure (see CLASSES section). The flags argument specifies a default set of flags (see FLAGS section).

The AG_ObjectInitStatic() variant of AG_ObjectInit() implicitely sets the AG_OBJECT_STATIC flag, indicating that the object's structure statically allocated (or allocated through a facility other than malloc(3)). The AG_ObjectInitNamed() variant either sets the object name with AG_ObjectSetNameS() if the name argument is non-NULL, or it implicitely sets the AG_OBJECT_NAME_ONATTACH flag if the name is NULL.

The function AG_ObjectAttach() attaches an object to a new parent object and AG_ObjectDetach() detaches an object from its current parent object. These operations raise attached and detached events. Prior to detaching the object, AG_ObjectDetach() cancels any scheduled AG_Timer(3) callback execution. If parent is NULL, AG_ObjectAttach() is a no-op.

The AG_ObjectMoveUp(), AG_ObjectMoveDown(), AG_ObjectMoveToHead() and AG_ObjectMoveToTail() functions move the object in the parent object's list of child objects. These functions are useful when the ordering is important - when the child objects represent a stack, for instance.

The AG_ObjectDelete() routine invokes AG_ObjectDetach() if the object is attached to a parent, followed by AG_ObjectDestroy().

AG_ObjectAttachToNamed() is a variant of AG_ObjectAttach() which looks up the parent inside the specified VFS using the pathname path.

AG_ObjectRoot() returns a pointer to the root of the VFS which the given object is attached to. AG_ObjectParent() returns the immediate parent of the given object.

The AG_ObjectFind() function returns the object corresponding to the specified path name. If there is no such object, NULL is returned.

AG_ObjectFindParent() returns the first ancestor of the object matching either the name or type string (whichever is non-NULL).

AG_ObjectFindChild() performs a name lookup on the immediate children of the specified object. The function returns the matching object if it was found, otherwise NULL.

AG_ObjectGetName() returns a newly-allocated string containing the full pathname of an object. The function returns NULL if insufficient memory is available. The AG_ObjectCopyName() function copies the object's pathname to a fixed-size buffer.

AG_ObjectLock() and AG_ObjectUnlock() acquire or release the locking device associated with the given object. This is a mutex protecting all read/write members of the AG_Object structure, except parent, root and the list of child objects cobjs which are all considered part of the virtual filesystem and are instead protected by AG_LockVFS(). The AG_ObjectLock() mutex can be used as a general-purpose locking device for the object. This mutex is guaranteed to be held during processing of all events posted to the object, as well as during object operations such as load() and save().

The AG_LockVFS() and AG_UnlockVFS() functions acquire or release the lock protecting the layout of the entire virtual system which the given object is part of.

Note that all lock/unlock routines above become no-ops if Agar is compiled with --disable-threads.

AG_ObjectSetName() updates the name of the given object. If the object is attached to a VFS, the VFS must locked.

AG_ObjectGenName() generates an object name string unique to the specified parent object obj. The class name is used as prefix, followed by a number. The name is written to the fixed-size buffer name of the given size len. In a multithreaded context, the name is only guaranteed to remain unique as long as the parent object's VFS is locked. The AG_ObjectGenNamePfx() variant generates a name using the specified prefix instead of the class name.

AG_ObjectSetAttachFn() and AG_ObjectSetDetachFn() allow custom "attach" and "detach" hooks to be registered. This is useful where it is necessary to control the order of the child objects (for example, in the AG_Window(3) system of Agar-GUI, the ordering of window objects is important as it determines the order of rendering). The hook function must insert/remove the child object directly from the parent's children list.

The AGOBJECT_FOREACH_CHILD() macro iterates child over every child object of parent. The child pointer is cast to the given structure type, without type checking. Example:

struct my_class *chld;

AGOBJECT_FOREACH_CHILD(chld, parent, my_class) {
	printf("Child object: %s\\n", AGOBJECT(chld)->name);
}

CLASSES

void AG_RegisterClass (AG_ObjectClass *classInfo)

void AG_UnregisterClass (AG_ObjectClass *classInfo)

void AG_RegisterNamespace (const char *name, const char *prefix, const char *url)

void AG_UnregisterNamespace (const char *name)

AG_ObjectClass * AG_LookupClass (const char *classSpec)

AG_ObjectClass * AG_LoadClass (const char *classSpec)

void AG_RegisterModuleDirectory (const char *path)

void AG_UnregisterModuleDirectory (const char *path)

int AG_OfClass (AG_Object *obj, const char *pattern)

AG_ObjectClass * AG_ObjectSuperclass (AG_Object *obj)

int AG_ObjectGetInheritHier (AG_Object *obj, AG_ObjectClass **pHier, int *nHier)

AGOBJECT_FOREACH_CLASS (AG_Object *child, AG_Object *parent, TYPE type, const char *pattern)

The AG_RegisterClass() function registers a new object class. classInfo should be an initialized AG_ObjectClass structure:

typedef struct ag_object_class {
	char hier[AG_OBJECT_HIER_MAX];	/* Full inheritance hierarchy */
	size_t size;             	/* Size of instance structure */
	AG_Version ver;          	/* Version numbers */
	void (*init)(void *obj);
	void (*reset)(void *obj);
	void (*destroy)(void *obj);
	int  (*load)(void *obj, AG_DataSource *ds, const AG_Version *ver);
	int  (*save)(void *obj, AG_DataSource *ds);
	void *(*edit)(void *obj);
	/* ... */
} AG_ObjectClass;

For example:

AG_ObjectClass MyClass = {
	"MyClass",
	sizeof(MyClass),
	{ 0,0 },
	Init,
	NULL,	/* reset */
	NULL,	/* destroy */
	Load,
	Save,
	NULL	/* edit */
};

We can define new operations (or other class-specific data) by overloading AG_ObjectClass. The AG_WidgetClass class in Agar-GUI, for instance, overloads AG_ObjectClass and adds 3 new methods:

typedef struct ag_widget_class {
	struct ag_object_class _inherit;
	void (*draw)(void *);
	void (*size_request)(void *, AG_SizeReq *);
	int  (*size_allocate)(void *, const AG_SizeAlloc *);
} AG_WidgetClass;

For example:

AG_WidgetClass agButtonClass = {
	{
		"Agar(Widget:Button)",
		sizeof(AG_Button),
		{ 0,0 },
		Init,
		NULL,	/* reset */
		NULL,	/* destroy */
		NULL,	/* load */
		NULL,	/* save */
		NULL	/* edit */
	},
	Draw,
	SizeRequest,
	SizeAllocate
};

The hier field of AG_ObjectClass specifies a inheritance hierarchy, in the form "MY_Superclass:MY_Subclass", or "MyNamespace(Superclass:Subclass)" . If implementing the class requires specific libraries available as dynamically loaded modules via AG_DSO(3), they may be appended to hier as a comma-separated list of library names preceded by "@". For example:

MyNamespace(Superclass:Subclass)@module1,module2

The size member specifies the size in bytes of the object instance structure. The ver member specifies an optional datafile version number (see AG_Version(3)).

init() initializes a new object instance. It is called after successful allocation of a new object by AG_ObjectNew() or AG_ObjectInit().

reset() restores the state of the object to an initial state. AG_ObjectLoad() invokes reset() implicitely prior to the load() operation. AG_ObjectDestroy() also invokes reset() implicitely prior to the destroy() operation.

destroy() frees all resources allocated by init() (excluding any resources already freed by reset()).

load() reads the serialized state of object obj from data source ds. It must return 0 on success or -1 if an error has occured. See: AG_DataSource(3) and SERIALIZATION section.

save() saves the state of obj to data source ds. It must return 0 on success or -1 if an error has occured. See: AG_DataSource(3) and SERIALIZATION section.

edit() is a user-defined / application-specific callback. In a typical GUI application, for example, edit() may be expected to create and return an AG_Window(3) or an AG_Box(3).

AG_UnregisterClass() removes the specified object class.

AG_RegisterNamespace() registers a new namespace with the specified name, prefix and informational URL. For example, Agar registers its own namespace using:

AG_RegisterNamespace("Agar", "AG_", "http://libagar.org/");

Once the namespace is registered, it is possible to specify inheritance hierarchies using the namespace format:

Agar(Widget:Button):MyLib(MyButton)

or the equivalent expanded format:

AG_Widget:AG_Button:MY_Button

The AG_UnregisterNamespace() function removes all information about the specified namespace.

The AG_LookupClass() function looks up the AG_ObjectClass structure describing the specified class (in namespace or expanded format). If there is no currently registered class matching the specification, AG_LookupClass() returns NULL.

AG_LoadClass() ensures that the object class specified in classSpec (see AG_RegisterClass() for details on the format) is registered, possibly loading one or more dynamic library files if they are specified in the string. Dynamic library dependencies are given in the form of a terminating @lib1,lib2,... string. AG_LoadClass() scans the registered module directories (see AG_RegisterModuleDirectory()) for the libraries specified in the string. Bare library names are given (the actual filenames are platform-dependent). Libraries that are found (and not already in memory) are loaded via AG_DSO(3). The first library must define a myFooClass symbol (where myFoo is the name of the class transformed from MY_Foo), for an AG_ObjectClass structure describing the class (i.e., the same structure that is passed to AG_RegisterClass()).

AG_UnloadClass() unregisters the specified class and also decrements the reference count of any dynamically-located module associated with it. If this reference count reaches zero, the module is removed from the current process's address space.

The AG_RegisterModuleDirectory() function adds the specified directory to the module search path. AG_UnregisterModuleDirectory() removes the specified directory from the search path.

The AG_OfClass() function evaluates whether the given object is an instance of the specified class. The pattern string may contain wildcards such as MyClass:* or MyClass:*:MySubclass:*. AG_OfClass() returns 1 if the object's class matches the given pattern.

The AG_ObjectSuperclass() function returns a pointer to the AG_ObjectClass structure for the superclass of an object. Exceptionally, if the object is an instance of the base class (AG_Object), a pointer to the AG_Object class is returned.

The AG_ObjectGetInheritHier() function returns into pHier an array of AG_ObjectClass pointers describing the inheritance hierarchy of an object. The size of the array is returned into nHier. If the returned item count is > 0, the returned array should be freed when no longer in use. AG_ObjectGetInheritHier() returns 0 on success or -1 if there is insufficient memory.

The AGOBJECT_FOREACH_CLASS() macro iterates child over every child object of parent which is an instance of the class specified by pattern. child is cast to the given structure type. Example:

struct my_class *chld;

AGOBJECT_FOREACH_CLASS(chld, parent, my_class, "MyClass") {
	printf("Object %s is an instance of MyClass\\n",
	    AGOBJECT(chld)->name);
}

DEPENDENCIES

int AG_ObjectInUse (AG_Object *obj)

AG_ObjectDep * AG_ObjectAddDep (AG_Object *obj, AG_Object *depobj, int persistent)

void AG_ObjectDelDep (AG_Object *obj, AG_Object *depobj)

Uint32 AG_ObjectEncodeName (AG_Object *obj, AG_Object *depobj)

int AG_ObjectFindDep (AG_Object *obj, Uint32 ind, AG_Object **pObject)

AG_ObjectInUse() returns 1 if the given object is being referenced by another object instance or 0 if it isn't.

AG_ObjectAddDep() either creates a new dependency upon depobj or increments the reference count if one exists. If the persistent flag is set, the reference is preserved in object archives. AG_ObjectDelDep() decrements the reference count upon depobj and removes the dependency if the count reaches zero (unless the object has the AG_OBJECT_PRESERVE_DEPS flag set).

AG_ObjectEncodeName() returns a serializable 32-bit handle representing the dependency between obj and depobj. It reserves the special values 0 (NULL reference) and 1 (self reference). The value of the handle corresponds to the index of depobj in the dependency table of obj plus 2.

AG_ObjectFindDep() resolves a dependency handle (previously generated by AG_ObjectEncodeName()). On success, a pointer to the object is returned in pObject and the function returns 0.

RELEASING RESOURCES

void AG_ObjectDestroy (AG_Object *obj)

void AG_ObjectReset (AG_Object *obj)

void AG_ObjectFreeEvents (AG_Object *obj)

void AG_ObjectFreeVariables (AG_Object *obj)

void AG_ObjectFreeDeps (AG_Object *obj)

void AG_ObjectFreeDummyDeps (AG_Object *obj)

void AG_ObjectFreeChildren (AG_Object *obj)

void AG_ObjectRemain (AG_Object *obj, Uint policy)

The AG_ObjectReset() function restores the state of an object to some initial state. It invokes the object's reset() method. reset() is expected to bring the object to a consistent state prior to deserialization (before the load() method is invoked).

The AG_ObjectDestroy() function frees all resources reserved by the given object (and any of its children that is not being referenced). It invokes reset() and destroy() for each class in the inheritance hierarchy. Note that AG_ObjectDestroy() also cancels any AG_Timeout(3) event scheduled for future execution. Unless the AG_OBJECT_STATIC flag is set, AG_ObjectDestroy() frees the structure with free(3).

Internally, AG_ObjectDestroy() invokes AG_ObjectFreeEvents(), AG_ObjectFreeVariables(), AG_ObjectFreeDeps() and AG_ObjectFreeChildren(). These functions may be used to explicitely reinitialize the event handler table (cancelling any scheduled timed event), clear the AG_Variable(3) table, or destroy all attached child objects.

AG_ObjectFreeChildren() releases all resources allocated by the child objects of a given parent. The assumes that none of the child objects are currently in use.

AG_ObjectFreeDummyDeps() cleans up the dependency table, removing any entry with a reference count of zero (which occurs in objects with AG_OBJECT_PRESERVE_DEPS set).

AG_ObjectRemain() specifies the behavior of AG_ObjectPageOut() once the object's data is no longer in use. The default behavior is to free the data. If an argument of AG_OBJECT_REMAIN_DATA is passed, the data will be kept in memory.

SERIALIZATION

int AG_ObjectLoad (AG_Object *obj)

int AG_ObjectLoadFromFile (AG_Object *obj, const char *file)

int AG_ObjectLoadFromDB (AG_Object *obj, AG_Db *db, const AG_Dbt *key)

int AG_ObjectLoadData (AG_Object *obj)

int AG_ObjectLoadDataFromFile (AG_Object *obj, const char *file)

int AG_ObjectLoadGeneric (AG_Object *obj)

int AG_ObjectLoadGenericFromFile (AG_Object *obj, const char *file)

int AG_ObjectSave (AG_Object *obj)

int AG_ObjectSaveAll (AG_Object *obj)

int AG_ObjectSaveToFile (AG_Object *obj, const char *path)

int AG_ObjectSaveToDB (AG_Object *obj, AG_Db *db, const AG_Dbt *key)

int AG_ObjectSerialize (AG_Object *obj, AG_DataSource *ds)

int AG_ObjectUnserialize (AG_Object *obj, AG_DataSource *ds)

int AG_ObjectReadHeader (AG_DataSource *ds, AG_ObjectHeader *header)

int AG_ObjectPageIn (AG_Object *obj)

int AG_ObjectPageOut (AG_Object *obj)

void AG_ObjectSetArchivePath (AG_Object *obj, const char *path)

void AG_ObjectGetArchivePath (AG_Object *obj, char *buf, size_t buf_len)

These functions implement serialization, or archiving of the state of an AG_Object to a flat, machine-independent binary format.

The AG_ObjectLoad*() family of functions load the state of an Agar object from some binary data source. The generic AG_Object state is loaded first, followed by the object's serialized data (which is read by invoking the load() function of every class in the inheritance hierarchy). The AG_ObjectLoad(), AG_ObjectLoadGeneric() and AG_ObjectLoadData() functions look for an archive file in the default search path (using the load-path setting of AG_Config(3)). The AG_ObjectLoadFromFile(), AG_ObjectLoadGenericFromFile() and AG_ObjectLoadDataFromFile() variants attempt to load the object state from a specific file. The AG_ObjectLoadFromDB() variant loads the object state from the given AG_Db(3) database entry.

The AG_ObjectSave*() family of functions serialize and save the state of the given object. The generic AG_Object state is written first, followed by the object's serialized data (which is written by invoking the save() function of every class in the inheritance hierarchy). The AG_ObjectSave() function creates an archive of the given object in the default location (i.e., the save-path setting of AG_Config(3)). The AG_ObjectSaveAll() variant saves the object's children as well as the object itself. AG_ObjectSaveToFile() archives the object to the specified file. AG_ObjectSaveToDB() archives the object to the given AG_Db(3) entry.

The AG_ObjectSerialize() function writes an archive of the given object to the specified AG_DataSource(3), and AG_ObjectUnserialize() reads an archive of the given object.

The AG_ObjectReadHeader() routine attempts to read the header of a serialized Agar object from a AG_DataSource(3) and returns 0 on success or -1 if no valid header could be read. On success, header information is returned into the header structure:

typedef struct ag_object_header {
	char hier[AG_OBJECT_HIER_MAX];	    /* Inheritance hierarchy */
	char libs[AG_OBJECT_LIBS_MAX];	    /* Library list */
	char classSpec[AG_OBJECT_HIER_MAX]; /* Full class specification */
	Uint32 dataOffs;                    /* Dataset offset */
	AG_Version ver;                     /* AG_Object version */
	Uint flags;                         /* Object flags */
} AG_ObjectHeader;

The AG_ObjectPageIn() function loads an object's data into memory and sets the AG_OBJECT_RESIDENT flag. AG_ObjectPageOut() checks whether an object is referenced by another object and if that is not the case, the data is serialized to permanent storage, freed from memory and AG_OBJECT_RESIDENT is cleared. Both functions return 0 on success or -1 if an error occured.

AG_ObjectSetArchivePath() sets the application-specific Archive Path attribute. For example, the "Save" feature of an editor application might use the Archive Path to remember an object's last successful Save or Export location, and AG_ObjectGetArchivePath() to later retrieve it. The Archive Path is a run-time attribute ignored by AG_ObjectSave().

FLAGS

The following public AG_Object flags are defined:

AG_OBJECT_FLOATING_VARS	Remove all entries of the AG_Variable(3) table in AG_ObjectLoad(). By default, the existing table is preserved and entries are created or replaced by items found in the archive.
AG_OBJECT_NON_PERSISTENT	Disables archiving of the object and its children. If set, AG_ObjectSave() becomes a no-op and AG_ObjectLoad() calls will fail.
AG_OBJECT_INDESTRUCTIBLE	Application-specific advisory flag.
AG_OBJECT_RESIDENT	The object's data exists in memory. Set by AG_ObjectPageIn() and AG_ObjectPageOut().
AG_OBJECT_PRESERVE_DEPS	Don't remove entries in the dependency table when their reference count reaches 0.
AG_OBJECT_STATIC	Object is statically allocated (or allocated via a facility other than malloc(3)). Disable use of free(3) by AG_ObjectDestroy().
AG_OBJECT_READONLY	Application-specific advisory flag.
AG_OBJECT_REOPEN_ONLOAD	If an edit() operation is defined, indicate that elements associated with its return value (such as GUI windows or elements in the case of a GUI application) should be recreated whenever AG_ObjectLoad() is used.
AG_OBJECT_REMAIN_DATA	Prevent the object's data from being freed by AG_ObjectReset() when a AG_ObjectPageOut() call is made and the reference count reaches zero. This is set by AG_ObjectRemain().
AG_OBJECT_DEBUG	Application-specific debugging flag.
AG_OBJECT_NAME_ONATTACH	Automatically generate a unique name for the object as soon as AG_ObjectAttach() occurs.
AG_OBJECT_CHLD_AUTOSAVE	Serialize the object's children in AG_ObjectSerialize().

EVENTS

The AG_Object mechanism generates the following events:

attached (void)	The object has been attached to another. This event originates from the parent object. The linkage lock is held during the execution of the event handler.
detached (void)	The object has been detached from its parent. The linkage lock is held during the execution of the event handler. This event originates from the parent.
child-attached (void)	Same as attached(), except that the event is sent from the child to the parent.
child-detached (void)	Same as detached(), except that the event is sent from the child to the parent.
renamed (void)	The object's name has changed.
object-post-load-data (const char *path)	Invoked by AG_ObjectLoadData(), on success. If the object was loaded from file, `path` is the pathname of the file.
bound (AG_Variable *V)	A new variable binding has been created, or the value of an existing binding has been updated; see AG_Variable(3) for details.

STRUCTURE DATA

For the AG_ObjectClass structure (see CLASSES section):

*char hier**	Full inheritance hierarchy.
size_t size	Size of instance structure (in bytes).
AG_Version ver	Versioning information (see AG_Version(3)).
*void (init)**	Initialization routine.
*void (reset)**	Cleanup routine (for AG_ObjectReset()).
*void (destroy)**	Final cleanup routine.
*int (load)**	Deserialization routine.
*int (save)**	Serialization routine.
*void (edit)*	Application-specific entry point.

The following read-only members are initialized internally:

*char name**	The name for this class only.
*char libs**	Comma-separated list of DSO modules.
*AG_ObjectClass super**	Pointer to the superclass.
TAILQ(AG_ObjectClass) sub	Direct subclasses of this class.

For the AG_Object structure:

char name[AG_OBJECT_NAME_MAX]	Unique (in parent) identifier for this object instance. May not contain " / ".
*char archivePath**	Application-specific path accessed by AG_Object{Get,Set}ArchivePath .() Typical application: Remember the last successful location for an editor's "Save" function.
*char save_pfx**	Path name prefix when saving to disk (after dir/ and before filename).
*AG_ObjectClass cls**	A pointer to the AG_ObjectClass for this object's class (see CLASSES section).
Uint flags	Option flags for this object instance (see FLAGS section).
TAILQ(AG_Event) events	Table of registered event handlers (set by AG_SetEvent(3)) and virtual functions (set by AG_Set<Type>Fn()).
TAILQ(AG_Timer) timers	List of active timers (see AG_Timer(3)).
TAILQ(AG_Variable) vars	Named variables (see AG_Variable(3)).
TAILQ(AG_ObjectDep) deps	Dependency table (see DEPENDENCIES ) .
TAILQ(AG_Object) children	List of child objects. The AGOBJECT_FOREACH_CHILD(), AGOBJECT_FOREACH_CHILD_REVERSE(), AGOBJECT_NEXT_CHILD(), AGOBJECT_LAST_CHILD() and AGOBJECT_FOREACH_CLASS() macros can be used to iterate over this list.

EXAMPLES

See tests/objsystem.c in the Agar source distribution.

HISTORY

The AG_Object interface appeared in Agar 1.0