Properties

A property is an element of the system that takes a set of objects (parameters) and returns exactly one object (the return value).

The type and the specifics of how to calculate each property are determined by the operator used to create the property.

Type constraint

Due to implementation features, all non-NULL property values returned must be of the same type. That is, a property cannot return, for example, a string for one set of parameters and a number for another.

The same constraint exists for each property parameter: a property cannot have a non-NULL value for an object collection in which, for example, the first parameter is a string, and at the same time have a non-NULL value for another object collection, in which the first parameter is an object.

Language

To create properties, use the = statement.

Examples

// property defined by the context-independent DATA property operator
cost 'Cost' (i) = DATA NUMERIC[12,3] (Item);

// property defined by expression
weightedSum 'Weighted amount' (a, b) = 2*a + 3*b;

// the caption of this property will be 'diff' and the parameters will be (a, b)
diff = a - b;

// property defined by DATA operator with additional property options
teamName 'Team name' = DATA BPSTRING[30](Team) IN baseGroup TABLE team;