Class within a class (as attribute) to call a method of the class that contains it-CodePudding

I am in the situation where I need a class that is within another (as an attribute) to communicate with the class that contains it, however, I cannot wrap my head around how to do it.
Take this situation as an example: There is a class HighSchoolClass that contains a list of Students that belong to that class, and HighSchoolClass has a method foo rearranging how the students are sited or whatever. But then, each student has the capability of asking if a rearranging can be made. So it would need to call the method for rearranging the class.

# Singelton
class HighSchoolClass:
  def __init__(self):
    self.list_of_students = # A list of instances of Student 
    self.profesor = ... 
  
  def rearrange_class():
    # do something


class Student:
  def ask_for_rearrange():
    # Needs to call rearrange_class() of the class he is in.

Is there any way of do this (ideally just calling it somehow)? Mind that rearrange_class() is not static. If it helps, the HighSchoolClass would be a singelton.

CodePudding user response：

Typically, you would explicitly give each Student a reference to the HighSchoolClass that they belong to. A simple example might look like

class Student:
    def __init__(self):
        self.class_ = None

    def add_class(self, class_):
        self.class_ = class_


class HighSchoolClass:
    def __init__(self):
        self.list_of_students = []
    
    def add_student(self, student):
        self.list_of_students.append(student)
        

class Registrar:
    def add_student_to_class(self, student, class_):
        class_.add_student(student)
        student.add_class(class_)

Note the use of a third class to both the student and the class. Otherwise, it's not obvious whether a student should be responsible for updating each class they join, or whether each class should update their students.

the_class = HighSchoolClass()
s1 = Student()
s2 = Student()
r = Registrar()

r.add_student_to_class(s1, the_class)
r.add_student_to_class(s2, the_class)

Now, each class and student has a reference to the other to be used as needed.