[Tutor] Creating instances (group program revisited)

[Benoit Dupire]

This is How I would solve the pb.

In fact, I don't think you have to have a 'Class' class, because the Class is
what you want to model. It's the whole!
Instead of the word 'class', I ll use  'course' because it is confusing with the
OO terminology...
What you want to model is what  a course id ?

The first actor is the teacher...
Yes.. because the teacher is going to make the group, not the students nor the
'course'....
A teacher has some the students.
A teacher can make some groups, print the list of  his students, and introduce
himself!
He can add some students to  his course...


Note1 : if you want your pb to be really OO, put  the loadFile function in a
class... (see below1)
Note2: it's better to have the split() logic in the loadFile function: the file
has to be decoded in this function  because if you want to store the student
names with a different syntax,  what you really want to do is to modify the
loadFile function and not the Student __init__ function.
In OO you have to define interfaces, that 's the encapsulation principle.
Now if  i change something, it's very 'local'...


import string

class Student:
    def __init__(self, ln, fn, gender):
        self.ln = ln
        self.fn = fn
        self.gender = gender
        self.group= 0

    def getName(self):
        return self.ln

    def __str__(self):
        return "%(ln)s %(fn)s %(gender)sin group: %(group)i" %self.__dict__

    def setGroup(self, groupNumber):
        self.group= groupNumber

class Teacher:
    def __init__(self, name):
        self.name=name
        self.studentList= []
        self.nbStudent = 0

    def __str__(self):
        return "My name is %s and my class has %i students" %(self.name,
self.nbStudent)

    def  addStudentFromFile(self, datafile):
            list= open(datafile, 'r').readlines()
            for entry in list:
                ln, fn, gender = entry.split(',')
                self.studentList.append(Student(ln, fn, gender))
            self.nbStudent+=len(list)

    def makeGroup(self, nbgroup):
            i=0
            for st in self.studentList:
                st.setGroup(i % nbgroup)
                i+=1

    def printStudentList(self):
            for st in self.studentList:
                print st

thePythonTeacher= Teacher('timothy')
thePythonTeacher.addStudentFromFile('toto.txt')
print thePythonTeacher
thePythonTeacher.makeGroup(4)
thePythonTeacher.printStudentList()




>>> reload(student)
My name is timothy and my class has 12 students
van Rossum Guido M
in group: 0
Boop Betty F
in group: 1
Gauld Alan M
in group: 2
Flintstone Wilma F
in group: 3
Rubble Betty F
in group: 0
Yoo Danny M
in group: 1
Wilson Tim M
in group: 2
Crawford Cindy F
in group: 3
Van Laningham Ivan M
in group: 0
Lutz Mark M
in group: 1
Ascher David M
in group: 2
Watters Aaron M
in group: 3
<module 'student' from 'C:\Python20\student.py'>



Yes, I enjoyed playing with your program!
The function to make the group is not perfect, but you end up with
Benoit