How To: Reference an existing Virtual Worlds object
Conceptually there are 4 object types in most programming systems:
Content Objects:
Contains property, method and event interfaces.
(Thing, World, Room, StateMachine, Portal, Artifact)Datum Objects:
These are kept as properties in Content and used as transients in Documents.
(Vector, Sound, Boundary, ObjReference, BSTRNames, Color, MenuItem, StoryName, Settings)Collection Objects:
Selections, One Dimensional Arrays, Lists of Content and Datum Objects
(PropertyMap, PropertyList, Module, Menu)Document Objects:
These are defined transient models the have at the root in one particular meaning.
(Method, Event, MenuItem, SearchResults, Story, Script )
This chotomy represents how the programmer uses the objects and not interface members. All of these objects have basic methods and properties for our convenience but those may mean very little to the object's intended purpose. You see the vagueness between Datum and Document objects since a Vector for instance can be looked at like a 'Document about placement containing x,y,z, rotation' or as 'Datum to be used for placement' The line between the two is this: A Document is a proprietary collection of Datum objects. When the document is destroyed the world state stays in tact. A document is like a transient package that is intended to do one thing. On the other hand, if Datum is destroyed then it can deface the Content object that held it as a property. (Later we'll go into more detail on this theory)
So in Prolog terms we access
Content objects like this:
thing(?Class,?Type,?ReferenceOrName,?MembersListBindings).
avatar(?Class,?Type,?ReferenceOrName,?MembersListBindings).
room(?Class,?Type,?ReferenceOrName,?MembersListBindings).
artifact(?Class,?Type,?ReferenceOrName,?MembersListBindings).
statemachine(?Class,?Type,?ReferenceOrName,?MembersListBindings).
Example:
An object created with:
Set NewThing = World.CreateInstance("Toy", "Artifact", User.Container)
could be referenced by
thing(artifact,
The functor being the class type:
| ModelKinds Enum |
Visual Basic/ActiveX | Virtual Worlds | Prolog | [X,*]ML |
| Property | INVOKE_PROPPUT / INVOKE_PROPGET | Thing.Properties | property(PropertyName,Owner,Type,Value) | |
| Method | INVOKE_FUNC | Thing.Methods (without on*) | method(MemberName,Owner,RetrunType,[parameterlist]) | |
| Event | INVOKE_EVENTFUNC ( major changes to notifacation system since some sites do not care for unsolicted messaging ) | Thing.Methods (with on*) |
event(MemberName,Owner,[parameterlist]) | |
| Content | INVOKE_PROPPUTREF/INVOKE_PROPGETREF | Thing.Contents | object(?Class,?Type,?ReferenceOrName,?MembersList), datum(?Type,?Value) |
|
| Parameter | INVOKE_CONST ( Not partucualry Correct) | Thing.Name | datum(?Type,?Value) |
Content Objects
Virtual World Objects
are of these types:
Thing
PropertyList
PropertyMap
....
From where the objects live
and are brokered
Type Conversion
1) Virtual Worlds Object
Collection vwsystem.dll/vwmm.dll
2) (soon ) Native COM Collection wrapped in
Morphism.Dll
3) Serialized Prolog Terms Representing Transient or InTransit objects
4) A markup language (Barely Implemeted)
| SITNAME_WINCOM | SITENAME_VWSERVER/SITENAME_VWCLIENT | SITENAME_PROLOG_CLIENT/SITENAME_PROLOG_SERVER | SITENAME_XML | |
| NodeKinds Enum | Visual Basic/ActiveX | Virtual Worlds | Prolog | [X,*]ML |
| Object | True Object (Set) | Thing | object(?Class,?Type,?ReferenceOrName,?MembersList) | XMLNodeElement |
| Collection | For Eachable Collection of Variants | PropertyMap, Menu | lists that only contain:
objects and values Sets |
XMLDOM or XMLElement |
| Value | String,Long,Byte,Integer,Long,Byte, VT_BSTR,VT_UI4, (etc) |
String,Long,Byte,Integer,Long,Byte, Single,Double |
atom, string, quoted terms | XMLNodeElement |
| Array | Array of Variants or a single UDT | PropertyList or Variant().. or a object that you/we have predefined a property list of named arguments such as: Sound, Module, Method, Vector, etc | ?funct(Arg1,Arg2,..) or Ordered Lists ./2 |
|
| FuncDesc | MemberName orAddressOf + DISPARAMS (VTABLE Entry) |
Method, MenuItem | :-/2 , -->,2 ,/2 ;/2 or
Canonical Terms or Static Predicates |
XSLDocument |
How to Access The Objects (The DOM )
Objects Non-determently
objects(?Class,?Type,?IDRef,?MemberList)
example:
findall(X,objects(avatar,thing,_Ref,[name=X|_]),ListOfNames).
objects(?Object). % Is the collection of all known objects
example:
findall(X,objects(object(class([avatar]),type([thing]),_Ref,[name=X|_])),ListOfAvatarNames).
member_unify(-Object,?NewMembers).
member_assert(-Object,-NewMembers).
member_retract(-Object,?Members).
member_retractall(-Object,?Members).
Walking an Object's Model
find_member(?Object,?MemberName,?Value)
walk_member(?StartObject,?MembersWalk,?Value)
example:
walk_member(objptr(345345),[error,description],datum(vt_bstr,Text)).
walk_member(_,[error,description],datum(vt_bstr,Text)).
walk_member(_,[_,description],datum(vt_bstr,Text)).
walk_member(_,[_,error,_],datum(vt_bstr,Text)).
walk_member(objptr(345345),[_,_,_],datum(vt_bstr,Text)).
walk_member(_,[error],Err),walk_member(Err,[description],datum(vt_bstr,Text)).
PrologVirtualWorlds Partial
Serialization of COM
(Component Object Models)
We will look at some object
models and see how they manifest in various places in our system. First
an object such as a newly created MSScriptControl.ScriptControl
as PrologVirtualWorlds sees it:
Morphism.Dll obj_pl(java_vbscript_engine,4,true) /* 4 levels deep, Ground_Instancing=True */
The SWI-Prolog kernel had
no problems working with an object in this form.
This is a ‘term serialization’ of the object’s model. The
MSScriptControl has ten Members marked as INVOKE_PROPGETable in COM.
I am of strong discipline that the future of properly written
windows COM must expose it’s members (in TypeLibs) in such a way as an object
model can be rendered with no side effects to the object (when using
INVOKE_PROPGET/GETREF). And members
where this is unsafe need to hide behind INVOKE_FUNCT interfaces.
We will use the rendered serialized model to classify objects and for
PrologVirtualWorlds to understand them later.
This model was constructed 4 levels deep and anything 5 or below was set
to Prologs ‘_’ this is so we can Unify objects later.
Look at this call for a non-instanced version (the objptr/1 and datum/2 which are ignored and only vt_variant and vt_empty are explored)
Morphism.Dll obj_pl(java_vbscript_engine,4,fail)
/* 4 levels deep, Ground_Instancing=False
*/
This information can be later
used to declare a new object. The smallest object declaration looks like this:
assert_object
(object(class([our,new,class]),type([we,ll,know,later]),_,[])).
This
creates a TypeLib info in for we_ll_know_later
that has no interface members.
To
add a member to it we use:
objects
(AnyObject),AnyObject = object(class(_),type([we|_]),_,_).