Version: 4.x

# Expression

An expression is a combination of property operators and parameters. When an expression is evaluated sequentially in priority order, all the operators are executed.

The result of that execution will be either a property or a parameter (in the case of single-parameter expression). Their value shall be called the value of the expression.

An expression can be described by the following set of recursive rules:

RuleDescription
`expression` := `parameter` | `constant` | `prefixOperator`A single parameter, constant, or non-arithmetic prefix operator
`expression` := `prefixArithmOp expression`A unary arithmetic prefix operator, with the expression passed to it as an operand
`expression` := `expression postfixOp`A unary postfix operator, with the expression passed to it as an operand
`expression` := `expression binaryOp expression`A binary operator with the expressions passed to it as operands
`expression` := `( expression )`Expression in parentheses

An expression cannot include context-independent property operators.

### Examples​

``CLASS Team;wins(team) = DATA INTEGER(Team);ties(team) = DATA INTEGER(Team);// The number of points received by the team for the matches playedpoints(Team team) = wins(team) * 3 + ties(team); // In this case, the expression is written to the right of the equal sign. It defines a new property called points.// When calculating the expression, two JOIN operators are first executed: wins(team) and ties(team), substituting // the team parameter in the wins and ties properties. Then the multiplication operator will be executed, // which will build a property that returns a number equal to the product of the return value of wins(team) // and the number 3. Then the addition operator will be executed, which will create a property that sums the return// values (wins(team) * 3) and ties(team). The resulting property will be the result of the expression.CLASS Game;CLASS BonusGame : Game;// The number of points per game. If the game is bonus, then 3, otherwise 2.gamePoints(Game game) = 2 (+) (1 IF game IS BonusGame); // In this example, the order of execution of the operators will be as follows: IS, IF, (+)``