Vision Terminology
? Command Starts a command line option.
. (Dot) Operator Operator used to terminate a keyword message.
, (Append) Message Message used to append objects into a single List object.
; Character Character used to terminate a statement in a program.
# Character Character used to introduce a comment.
\ Character Character used to indicate that the next character should be interpretted as a literal. It is used to include special characters in names.
! Character Character used to define a new variable.
<- and -> Messages Assignment messages used to update the value of a property or variable.
^ Character Character used to introduce a magic word.
[ ] Characters Square brackets define a Block, a program representing a deferred sequence of actions.
| Character Veritcal bars define the start and end of the named portion of a block.
" Character Double quotes define the start and end of strings.
' Character Single quotes define the start and end of selectors.
:selector (see Intensional Form)
selector: (see Keyword)
Argument (see Parameter)
Assignment (see <- character)
batchvision Name of the executable program that directly accesses the Vision database.
Binary Message Special type of message requiring one parameter.
Block (see [ ] )
Boolean Class provides protocol for logical values represented by its subclasses: TRUE and FALSE.
Class Describes a group of similar objects.
Class Constant Property of a class which returns an identical value for each instance of its class.
Class Descriptor Maintains information about a class in the database.
Collection Superclass of List, IndexedList, and TimeSeries classes.
Context Environment in which a message is executing.
Context Switch Change the default search path for message resolution.
Control Structure Controls the order of expression evaluation.
Currency Class representing different monetary units and protocol for restating monetary values.
Date Class representing specific calendar dates.
DateOffset Class representing increments that can be added to or subtracted from dates.
DateRange Class representing a range of dates.
Default Instance Initial instance created when a new class is created.
Dictionary Class used to uniformly manage names for a set of related objects.
Entity Abstract class that organizes classes whose instances represent real-world entities such as companies, products, and industries.
Environment Execution level containing any number of local messages and an implied search path for message resolution.
Expression Series of messages applied in succession.
FALSE Subclass of Boolean representing FALSE values.
Fatal Error Indicates that a fatal Vision error has occurred.
Fixed Property Attribute of an object that does not vary over time.
IndexedList Subclass of Collection containing one or more objects that are accessed either by user-defined index or as a set.
Inheritance Path Class hierarchy for an object representing the search order used to resolve messages.
Instance Individual object in a class.
Intensional Form Form for returning a message that can be updated (properties) and displayed (methods).
Keyword Name of a parameter in a keyword message followed by the : character.
Keyword Message Message with one or more parameters composed of one more keywords, one preceding each parameter.
List Subclass of Collection containing one or more objects that are accessed either by position or as a set.
Literal Number, string, block, or magic word. A literal must be the first object in an expression.
Magic Word One of a set of messages to the literal ^ ("Root").
Message Request for an object to carry out one of its operations.
Message Descriptor Maintains information about a message in the database.
Method Actual program used to implement a procedural message.
NA Object representing a value that is not available.
Name String used to name an object or a message.
Navigation Process of using messages to get from one object to another.
Number Class whose instances represent numerical values and superclass of the Integer, Double, and Float classes.
Object Basic unit of information representation.
Offset (see DateOffset )
Parameter Expression providing additional information for keyword and binary messages.
Precedence Order Unambiguous rules for ordering the execution of a Vision expression.
Primitive Built-in message that cannot be viewed or modified by the user.
Program One or more expressions that function together as a unit.
Property Attribute of an object.
Read-Eval-Print Error (see Fatal Error )
Recipient Object to which a message is being sent.
Resolving the Message Search that is performed to determine the version of the message to use.
Schema ToolKit used to manage information about the classes and messages in the Vision database.
Selector (see Name )
Selector Not Found Error resulting from requesting an undefined message.
Shadow Instance Psuedo-instance used as a surrogate for a deleted instance.
Specialization Creation of a new class.
Statement Single expression in a program.
String Class whose instances represent sequences of one or more characters.
Subclass Class that inherits properties and methods from another class.
Superclass Class from which properties and messages are inherited.
Syntax Error Error resulting from incorrectly formulated expressions.
Temporary Work Space Global environment for a session not started with an explicit object space.
TimeSeries Subclass of Collection containing one or more objects that are accessed either by date or as a set.
Time Varying Property Attribute of an object that can vary over time.
Top Level Object Space Global environment for the session.
TRUE Subclass of Boolean representing TRUE values.
Unary Message Message without arguments.
Undefined (see NA )
Variable Name used to store the value of an object.