import ecore : 'http://www.eclipse.org/emf/2002/Ecore#/';

package tutorial : tut = 'http://www.eclipse.org/mdt/ocl/oclinecore/tutorial'
{
  class Library
  {
    attribute name : String;
    property books#library : Book[*] { composes };
    property loans : Loan[*] { composes };
    property members#library : Member[*] { composes };
  }
  
  class Book
  {
    invariant SufficientCopies:
      library.loans->select(book=self)->size() <= copies;
    attribute name : String;
    attribute copies : Integer;
    property library#books : Library[?];
    property loans : Loan[*] { derived,volatile }
    {
      derivation: library.loans->select(book=self);
    }
    operation isAvailable() : Boolean[?]
    {
      body: loans->size() < copies;
    }
  }
  
  class Member
  {
    attribute name : String;
    property library#members : Library[?];
  }
  
  class Loan
  {
    property book : Book;
    property member : Member;
    attribute date : ecore::EDate[?];
  }
}