E-learning Platform

Build the classes of an e-learning platform: courses, students and instructors. Students and instructors are both people, so they share a parent class.

The objects must not point at each other: a course stores the emails of its students and the name of its instructor, and students and instructors store course titles. A method that needs a course receives it as an argument.

Person in person.gd: the constructor takes person_name and email and stores them. _to_string() returns NAME (EMAIL).

Course in course.gd:

• Properties: title, max_capacity, instructor_name (starts as ""), and the Array[String] student_emails and completed_emails.
• The constructor takes the title and the capacity, which defaults to 30.
• A signal course_full(title: String), emitted by add_student() when it takes the last free seat.
• add_student(email) -> bool: returns false when the course is full or the email is already a student; otherwise adds the email and returns true.
• remove_student(email) -> bool: removes a current student, false if the email is not one.
• mark_completed(email) -> bool: moves a current student to completed_emails, false if the email is not a current student.
• assign_instructor(instructor) -> bool: stores the instructor's name, or returns false when the course already has one.
• _to_string() returns TITLE: N/CAPACITY students, M completed, instructor: NAME, with none when there is no instructor.

Student in student.gd extends Person and keeps its constructor. It has two Array[String] of titles, enrolled and completed:

• enroll(course: Course) -> bool: false when the course is already in enrolled or completed, or when course.add_student() refuses; otherwise adds the title and returns true.
• unenroll(course: Course) -> bool: only for an enrolled course; removes the student from the course and the title from enrolled.
• complete_course(course: Course) -> bool: only for an enrolled course; calls course.mark_completed() and moves the title from enrolled to completed.
• _to_string() returns Student , the text of Person, then : N enrolled, M completed.

Instructor in instructor.gd extends Person. Its constructor takes person_name, email and expertise, and it keeps an Array[String] course_titles:

• assign_to_course(course: Course) -> bool: calls course.assign_instructor() with its name; on success adds the title and returns true.
• _to_string() returns Instructor , the text of Person, , EXPERTISE: and the titles joined with , , or no courses.

The supplied code reads commands with fields separated by | and connects to course_full to print Course full: TITLE. For this input:

course Python 101|2
course Data Science
student Ana|ana@mail.com
student Ben|ben@mail.com
instructor Grace Hopper|grace@mail.com|Compilers
enroll ana@mail.com|Python 101
enroll ben@mail.com|Python 101
enroll ben@mail.com|Data Science
assign grace@mail.com|Python 101
report

the output is:

Enroll Ana in Python 101: true
Course full: Python 101
Enroll Ben in Python 101: true
Enroll Ben in Data Science: true
Assign Grace Hopper to Python 101: true
Python 101: 2/2 students, 0 completed, instructor: Grace Hopper
Data Science: 1/30 students, 0 completed, instructor: none
Student Ana (ana@mail.com): 1 enrolled, 0 completed
Student Ben (ben@mail.com): 2 enrolled, 0 completed
Instructor Grace Hopper (grace@mail.com), Compilers: Python 101

Your code goes in person.gd, course.gd, student.gd and instructor.gd. main.gd holds the supplied input/output code and cannot be edited.