What is a common restriction when defining a property with a Declare Expression?

A Declare Expression in Pega is used to automatically compute the value of a property based on other properties within the system. One key restriction of Declare Expressions is that they cannot set a property to a constant value. This is because the primary purpose of a Declare Expression is to establish a dynamic calculation or relationship between properties rather than to assign a fixed, unchanging value.

By design, a Declare Expression derives its value based on the input from other properties, ensuring that the value can change according to the data state. This dynamic nature facilitates more robust business logic as it allows the system to automatically update calculated values when any of the underlying properties change.

In summary, the focus of a Declare Expression is on the computation based on existing properties rather than simply assigning constant values, highlighting its role in creating intelligent and responsive applications.