Vision Class Cross Reference

Predefined Class Hierarchy

Your Vision database comes with a number of pre-defined classes. These classes include an initial set of methods which you can modify and extend. All classes are direct or indirect subclasses of the class Object. You can also define any number of additional subclasses.

The pre-defined class hierarchy is illustrated below:

Object
   Boolean
   Bridge
   BuiltInWorkspace
      CoreWorkspace
   DBEntity
   DataRecord
   DateRange
   Dictionary
   Entity
      Classification
      Currency
      DataSource
   FixedProperty   
      TimeSeriesProperty 
   Function
      ComputedFunction 
         Block
         Method
         Primitive
      EnumeratedFunction
         Collection
            IndexedCollection
               IndexedList
               TimeSeries
            SequencedCollection
               List 
         Value
   IncorporatorPrototype
   LinkRecord
   Ordinal
      Date
      DateOffset
      Number
         Double
         Float
         Integer 
      String
   PrivateRecord
   Selector
   ToolKit
      Environment MaintenanceTools
      FormatTools
      Interface
      OpenVision
      Schema 
   Undefined
   Utility

The Boolean Class

This class provides protocol for logical values. Logical values are represented by the two subclasses of Boolean - TRUE and FALSE.

The DateRange Class

This class is defined by specifying a starting date, an ending date an an increment. Starting and ending dates can be any valid absolute or relative date. The increment is an instance of one of the DateOffset classes.

The Dictionary Class

The subclasses of the Dictionary class are used to name related objects in a homogeneous way.

The Entity Class

The subclasses of the Entity class are used to describe real-world entities such as companies, countries, and products. Instances of these classes are usually named and can be referenced directly or used as part of a list.

The Function Classes

This class is an abstract class that is used to organize the classes in the hierarchy that can be evaluated. Two major subclasses are defined: ComputedFunction and EnumeratedFunction. The class ComputedFunction is an abstract class that is used to organize the Function classes in the hierarchy that are computed rather than enumerated. The class EnumeratedFunction is an abstract class that is used to organize the Function classes in the hierarchy that are enumerated rather than computed. These classes are also divided into several subclasses.

Three subclasses of the class ComputedFunction have been defined: Block, Method and Primitive. Instances of these classes all represent a type of function which evaluates by computation. A Block is a set of one or more expressions that are viewed together as a unit. Methods are a special form of block that are created and used internally. The class Primitive represents methods that are implemented primitively in Vision. Although messages that are primitives are not distinguishable from other messages from a usage perspective, these messages cannot be directly altered inside Vision.

Two subclasses of the class EnumeratedFunction have been defined: Collection and Value. Instances of these classes all represent a type of function which evaluates by enumerating elements. The class Collection is an abstract class that is used to organize multi-valued EnumeratedFunction classes in the hierarchy. The instances of the class Value are single-valued enumerated functions. The class Collection includes two types of collections: IndexedCollection and SequencedCollection. The class IndexedCollection is an abstract class that is used to organize the collections that are indexed, IndexedList and TimeSeries. The class SequencedCollection is an abstract class that is used to organize the collection subclass that is not indexed, the List class.

The Ordinal Classes

This class is an abstract class that is used to organize the classes in the hierarchy whose instances can be compared along a linear dimension. Subclasses of the class Ordinal are Character, Date, DateOffset, Number and String.

The instances of the class Date represent a specific day in the calendar. Each date encompasses a day, month, and year. The class DateOffset is an abstract class that supports the protocol for different date increments: BusinessDays, Days, MonthBeginnings, MonthEnds, Months, QuarterBeginnings, QuarterEnds, Quarters, YearBeginnings, YearEnds, and Years.

The class Number is used to organize the numeric classes Double, Float, and Integer. The instances of the class String are objects that represent sequences of characters.

The Selector Class

The instances of this class are objects that represent strings used for names in the system. Each selector is unique; there can never be two selectors with identical character sequences defined for the same class.

The ToolKit Class

Subclasses of this class are used to organize packages of classes and messages offered as a unit to perform a set of related functions. Built-in ToolKits include The OpenVision ToolKit, The Schema ToolKit, and The UserInterface ToolKit.

The Utility Class

This class is used to organize miscellaneous utility operations. This class does not have any instances. It does respond to a set of primitive messages which execute utility functions.

The Undefined Class

This class is used to represent values that are not available (NA).

The Application Classes

These classes are used to organize the data and manage the navigations, access and processing rules associated with specific application.