Object composition
（重定向自User defined type）
![Aggregation in COM](/Images/godic/202502/19/Simple_COM_aggregation_diagram.svg5413.png")
In computer science, object composition (not to be confused with function composition) is a way to combine simple objects or data types into more complex ones. Compositions are a critical building block of many basic data structures, including the tagged union, the linked list, and the binary tree, as well as the object used in object-oriented programming.