Is abstract class field in python possible?

Python Programming Modify Student Class

• Python Programming Question Modify the student class by adding a mutator method that records a grade for the student. Here is the specs for the new student: addGrade(self, gradePoint, credits) gradePoint is a float that represents a grade(e.g. A = 4.0, A- = 3.7, B+ = 3.3 etc.) and credits is a float indicating the # of credit hours for the class. Modifies the student object by adding this grade info. Use the updated class to implement a simple program for calculating GPA. Your program should create a new student object that has 0 credits and 0 quality points.(the name is irrelevant). Your program should then prompt the user to enter course information(gradepoint, credits) and then print out the final GPA acheived. This is the student class to be modified: class Student: def __init__(self, name, hours, qpoints) self.name = name self.hours = float(hours) self.qpoints = float(qpoints def getName(self): return self.name def getHours(self): return self.hours def getQpoints(self): return self.qpoints def gpa(self): return self.qpoints/self.hours def makestudent(infoStr): name, hours, qpoints = string.split(infoStr, "\t") return Student(name, hours, qpoints) def main(): filename = raw_input(Enter name the grade file: ") infile = open(filename, 'r') best = makeStudent(infile.readline()) for line in infile: s = makeStudent(line) if s.gpa() > best.gpa(): best = s infile.close() print "The best student is: "), best.getName()

• Answer:

  Dear babutche, The makestudent() and main() methods in your sample code are irrelevant to the calculation of cumulative GPA, so I have omitted them from my own code. I have included many comments in the code to help you understand how the user feedback loop works. I ran the program from a UNIX command line to obtain the following test transcript. $ python student.py Enter grade for next course, or nothing to finish: 3.0 Enter number of credit hours for this course: 10 Enter grade for next course, or nothing to finish: 4.0 Enter number of credit hours for this course: 30 Enter grade for next course, or nothing to finish: 3.7 Enter number of credit hours for this course: 20 Enter grade for next course, or nothing to finish: 3.3 Enter number of credit hours for this course: 20 Enter grade for next course, or nothing to finish: *** final GPA = 3.625 The code listing is below. Regards, leapinglizard #===begin student.py class Student: def __init__(self, name, hours, qpoints): self.name = name self.hours = float(hours) self.qpoints = float(qpoints) def getName(self): return self.name def getHours(self): return self.hours def getQpoints(self): return self.qpoints def gpa(self): return self.qpoints/self.hours # new mutator method as per specification def addGrade(self, gradePoint, credits): self.hours += credits self.qpoints += credits*gradePoint if __name__ == '__main__': # output messages prompt_grade = 'Enter grade for next course, or nothing to finish: ' prompt_credits = 'Enter number of credit hours for this course: ' error_float = 'error: expected a floating-point number' # make a new Student object stu = Student('stu', 0.0, 0.0) # user-feedback loop while 1: # prompt user to enter a grade grade_str = raw_input(prompt_grade) # quit if no grade is entered if grade_str.strip() == '': break try: # convert input to a floating-point value grade = float(grade_str) except ValueError: # if input cannot be converted, restart feedback loop print error_float continue # prompt user to enter the number of credits credits_str = raw_input(prompt_credits).strip() try: # convert input to a floating-point value credits = float(credits_str) except ValueError: # if input cannot be converted, restart feedback loop print error_float continue # update the student's grades stu.addGrade(grade, credits) # after user has entered all grades, compute the cumulative GPA if stu.getHours() == 0.0: # can't compute GPA if hours = 0 print '*** zero credit hours recorded' else: # otherwise, output cumulative GPA and finish print '*** final GPA =', stu.gpa() #===end student.py