VASSAL Reference Manual

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Properties

A Property is like a variable in programming: it has a value which can be referenced by including its name in Expressions, Message Formats and other similar fields. Most types of Property have their values change through the course of the game. Some Properties can have their values set by commands provided in Game Pieces themselves; others have their values set by the system and cannot be changed from within the module.

Each Game Piece has its own set of properties (each with a name and a value) that can be used for identification by various components. You can add your own new properties to a Game Piece explicitly by adding Dynamic Property traits to create values which can be changed during the course of the game and Marker traits for properties whose values will remain constant. System-defined properties are also added implicitly when other traits are added (see below). Global Properties can also be defined for a Zone, a Map or for the entire module. If a referenced Property name is not defined in a Game Piece, the VASSAL looks for the value in the Zone containing the piece, then in the Map containing the piece, then in the module.

Properties can be matched using Expressions like name == value for an exact match, name != value for a non-match, or name =~ value for a regular expression match. For properties that return a numeric value (e.g. the level in a Layer) you can use <, <=, >, and >=. You can combine expressions using && for logical AND and || for a logical OR.

Components that use properties

Any Message Format defined in a Game Piece will substitute values for the properties defined on that Game Piece.
The Global Key Command component uses properties to determine which pieces will respond to the command.
The Game Piece Layers component uses properties to determine relative ordering when drawing pieces on the map.
The Trigger Action trait uses properties to determine when to fire a Key Command or Named Key Command .
The Text Label trait substitutes properties when setting the text of the label.
A Zone uses properties to specify a Zone Highlighter.

Properties defined by Game Pieces

The Basic Piece defines properties related to a piece’s name, location, side, and whether it’s selected.
The Layer trait defines properties related to the state of that Layer.
The Rotate trait defines properties related to the current facing of the piece.
The Text Label trait returns the value of the label as a property.
The Marker trait allows you to define your own static properties.
The Dynamic Property trait allows you to define your own changeable properties.
The Mark When Moved trait sets a property when a piece has moved.
The Mask trait sets a property when the piece is masked.
The Invisible trait sets a property when the piece is invisible.
The Property Sheet trait exposes a set of user-editable properties.

Properties defined by other components

The Global Property component defines properties for a Zone, Map or the module.
The Global Options component allows you to tie property values to preferences settings.
The results of a roll by a Dice Button is exposed as a property
A Deck component exposes the number of cards remaining as a Map-level property.

Handy Combined List of VASSAL-defined Properties for Game Pieces

Property

Trait

Description

BasicName