What is the primary purpose of a Declare Expression?

The primary purpose of a Declare Expression is to calculate property values dynamically. This feature allows for the automatic update of properties based on changes to related properties or certain conditions within the application. When defined, a Declare Expression continuously evaluates its expression and will update the target property whenever any of the input properties change or are saved, ensuring that the data is always current and aligned with the business logic. This dynamic calculation helps maintain consistency and accuracy in processing without requiring additional user intervention.

The other choices focus on functionalities that, while relevant to the overall capabilities of the Pega platform, do not accurately describe the specific role of a Declare Expression. User inputs pertain to how data is collected from application users, class rules relate to the organization of rules within the Pega architecture, and UI components involve elements of user interface development. None of these directly capture the essence of what a Declare Expression accomplishes in automated property value calculation.