Student Result Management System Class Diagram

classDiagram
  class Student {
    +String rollNo
    +String name
    +enrolments() List~Enrolment~
  }
  class Subject {
    +String code
    +String title
    +int credits
  }
  class Enrolment {
    +String semester
    +attendancePercent() decimal
    +totalMarks() decimal
  }
  class Mark {
    +String assessment
    +decimal marks
    +decimal maxMarks
  }
  class AttendanceRecord {
    +Date classDate
    +bool present
  }
  class GradingPolicy {
    <<interface>>
    +gradeFor(decimal percent) String
  }
  class AbsoluteGrading {
    +gradeFor(decimal percent) String
  }
  class RelativeGrading {
    +gradeFor(decimal percent) String
  }
  class ResultCalculator {
    +calculate(Student, String semester) SemesterResult
  }
  class SemesterResult {
    +decimal sgpa
    +decimal cgpa
  }
  class ReportCard {
    +generatePdf() void
  }
  Student "1" --> "many" Enrolment
  Enrolment --> Subject
  Enrolment "1" *-- "many" Mark
  Enrolment "1" *-- "many" AttendanceRecord
  GradingPolicy <|.. AbsoluteGrading
  GradingPolicy <|.. RelativeGrading
  ResultCalculator --> GradingPolicy
  ResultCalculator ..> SemesterResult : creates
  ReportCard o-- SemesterResult