Feature #1617: Scoped definitions and variables
Evaluation of runtime conditions
Some conditions (e.g., scopes) can only be determined at runtime as the game world is dynamically changing. This means that evaluation of the condition must be extremely fast, and it should not be done if the result is already known due to a previous evaluation.
A "condition" in this case would be a simple expression consisting of arithmetic and logical operations. In practice, one would have to observe the condition operands for changes and only re-evaluate if one of them changes its value.
One implementation possibility would be to use the classes of the Doomsday Script expression evaluator directly.