Python3 挑战实验 -- 类和Collection（实验楼）

#!/usr/bin/env python3

import sys
from collections import Counter

class Person(object):
    
    def __init__(self, grade):
        self.grade = grade

    def get_grade(self):
        return self.grade

class Student(Person):

    def __init__(self, grade):
        Person.__init__(self, grade)

    def get_grade(self):
        x = Counter(self.grade)
        return "Pass: {}, Fail: {}".format(len(self.grade) - x['D'], x['D'])
        
class Teacher(Person):

    def __init__(self, grade):
        Person.__init__(self, grade)

    def get_grade(self):
        results = []
        grades = Counter(self.grade).most_common(4)
        for key, value in grades:
            s = key + ":" + str(value)
            results.append(s)
        return ", ".join(results)

if __name__ == '__main__':
    if sys.argv[1] == 'student':
        student = Student(sys.argv[2])
        print(student.get_grade())
    else:
        teacher = Teacher(sys.argv[2])
        print(teacher.get_grade())

1.if __name__ == '__main__':是程序的入口。当.py文件被直接运行时，if __name__ == '__main__'之下的代码块将被运行；当.py文件以模块形式被导入时，if __name__ == '__main__'之下的代码块不被运行；

2.python3严格区分Tab和空格。注意！