Declarative Objectivity (DO) Language : Expressions : System Values
System Values
System values are expressions that return values produced by the DO system or by the computer on which DO is running.
Note:For a current list of supported system values, you can run the following tool from a command prompt:
objy ListSystemValues
Date and Time Values
 
Expression
Description
Result Type
$$NOW
Returns a datetime value representing the current date and time, expressed in the Coordinated Universal Time (UTC) standard. UTC is the time as measured at zero degrees longitude, the UTC origin point.
DateTime
$$TODAY
Returns a date value representing the current date.
Date
Quick Look 
Return the reservations that are less than a day old:
FROM Reservation WHERE ($$NOW - timestamp) < INTERVAL{days:1} RETURN *;
Discussion 
Date and time system values are commonly used as operands in operator expressions, or as attribute values in assignment operations.
Context-Related Values
 
Expression
Description
Result Type
$$ID
Returns the object identifier of the current context object.
Reference
$$THIS
Returns the current context object as an object.
Object
Quick Look 
Return the reward points of a Customer object with the specified object identifier.
FROM Customer WHERE $$ID == 3-3-1-20 RETURN rewardPoints;
Discussion 
Context-related system values are commonly used as operands in operator expressions.