What is Composition ?

Composition

• This is a stringer form of aggregation.
• It expresses relationship between a ‘container’ and ‘contained’ or ‘part’.
• The container is responsible for creation and deletion of its parts.

Example

In composition, the attribute is contained by value.

Composition = Aggregation with lifetime control

Shown  by filled diamond at the "owner" side

Lifetime control: Construction and destruction controlled by "owner" →  Call constructors and destructors (or have somebody else do it)

Lifetime control implied.

Lifetime control can be tranferred.