How to Use Abstract Data Types (correction)

How to Use Abstract Data Types (correction)

[adam]

Whoops, in my previous posting I forgot to declare my procedures as
abstract.  Thus, my package spec should be:

    package Library_Package is

        type Library is abstract tagged null record;
        type Book is abstract tagged null record;

        type Scan_Info is abstract tagged null record;

        ... procedure(s) to set up a new Library object

        procedure Scan_By_Title (Lib            : in Library;
                                 Reg_Expression : in String;
                                 Scan           : out Scan_Info;
                                 RE_Error       : out Boolean)
            is abstract;
        function More_Books (Scan : Scan_Info) return Boolean
            is abstract;
        procedure Next_Book (Scan     : in out Scan_Info;
                             Bk       : out Book)
            is abstract;
        procedure Close_Scan (Scan : in out Scan_Info)
            is abstract;

        ... etc.

    end Library_Package;

                                -- Adam


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