I am currently studying an example from an online course to design a class diagram for a Library Management System.
However, I am confused with this example:
I can't really understand the purpose of creating two classes: Book
and Book Item
.
Couldn‘t I just insert attributes from Book Item
class into the Book
class and keep only a single class of the two?
This is an interesting example:
Book
refers to an book in the catalogue of the publisher or the library. It has an ISBN to uniquely identify it, a title, an author and so on.BookItem
refers to a copy of that book that is owned by the the library and is lend to the users.But this example requires improvements:
BookItems
may refer to the same Book
, and the model does not capture this reality.