IF ... THEN operator
The IF ... THEN
operator creates a property that implements selection with one condition (single form).
Syntax
IF condition
THEN value
[ELSE alternativeValue]
Description
The IF ... THEN
operator creates an action that implements conditional selection. The condition is defined using a property. If this condition is met, that is, the value of the property does not equal NULL
, then the value of the created property will be the value of the property specified in the THEN
block; otherwise, the value will be the value of the property in the ELSE
block, or NULL
if no ELSE
block was specified.
Parameters
-
condition
Expression defining a condition.
-
value
An expression whose value will be the value of the created property if the condition is met.
-
alternativeValue
An expression whose value will be the value of the created property if the condition is not met.
Examples
price1 = DATA NUMERIC[10,2] (Book);
price2 = DATA NUMERIC[10,2] (Book);
maxPrice (Book b) = IF price1(b) > price2(b) THEN price1(b) ELSE price2(b);
// if h is of another class, it will be NULL
sex (Human h) = IF h IS Male THEN 'Male' ELSE ('Female' IF h IS Female);
isDifferent(a, b) = IF a != b THEN TRUE;