Deallocation of storage

Storage may be deallocated (released) manually, or you can leave it to the system to do it automatically.

Automatic on procedure exit

• safe, simple
• no dangling pointers

Programmer can deallocate space manually

• UNCHECKED_DEALLOCATION
• programmer deallocates storage
• care: avoid dangling pointers

Automatic deallocation

      about to exit                              after exit

Manual deallocation

Code for manual deallocation

    with UNCHECKED_DEALLOCATION;
    procedure main is

        type T  is ... ; -- type definition
        type T_ptr is access T;

        procedure deallocate_T is new
            unchecked_deallocation (T,T_ptr);

        PT : T_ptr;

    begin
          ...
        PT := new T;      -- allocate from heap
          ...
        deallocate_T (PT);  -- return to heap
          ...
    end;