A good deal of code in software systems accumulates information. The refactorings in this section target the improvement of code that accumulates information within an object or across several objects.
A Collecting Parameter [Beck, SBPP] is an object that visits methods in order to accumulate information from them. The visited methods may reside within one object or many objects. Each visited method provides the Collecting Parameter with information. When all relevant methods have been visited, the accumulated information can be obtained from the Collecting Parameter.