Python类Setter方法仅适用于

Question

class courseInfo(object):

    def __init__(self, courseName):
        self.courseName = courseName
        self.grade = "No Grade"


    def setGrade(self, grade):
        if self.grade == "No Grade":
            self.grade = grade

    def getGrade(self):
        return self.grade



class edx(object):
    def __init__(self, courses):
        self.myCourses = []
        for course in courses:
            self.myCourses.append(courseInfo(course))


    def setGrade(self, grade, course="6.01x"):
        """
        grade:integer greater than or equal to 0 and less than or equal to 100
        course: string 

        This method sets the grade in the courseInfo object named by `course`.   

        If `course` was not part of the initialization, then no grade is set, and no
        error is thrown.

        The method does not return a value.
        """
        for crs in self.myCourses:
            if crs.courseName == course:
                crs.setGrade(grade)



    def getGrade(self, course="6.02x"):
        """
        course: string 

        This method gets the grade in the the courseInfo object named by `course`.

        returns: the integer grade for `course`.  
        If `course` was not part of the initialization, returns -1.
        """
        for crs in self.myCourses:
            if crs.courseName == course:
                return crs.getGrade()
            else:
                return -1            

我对上述代码的测试用例是：

> edX = edx( ["6.00x","6.01x","6.02x"] )
> edX.setGrade(100, "6.00x")
> edX.getGrade("6.00x")
> 100

到目前为止还不错，但是运行edX.setGrade(50, "6.00x")并不需要，而且getGrade仍然返回100。而且，为6.01和6.02设置等级似乎不起作用，而且getGrade总是返回-1。你知道吗

任何帮助指点将不胜感激！你知道吗

（完全披露：这是一个在线课程。但我不认为这里有任何破坏者，我真的想了解发生了什么。（Tks）

Answer 1

当然，它只工作一次，你这样编码：

def setGrade(self, grade):
    if self.grade == "No Grade":
        self.grade = grade

设置等级后，测试self.grade == "No Grade"不再为真。你知道吗

在getGrade()方法中确实存在问题：

for crs in self.myCourses:
    if crs.courseName == course:
        return crs.getGrade()
    else:
        return -1            

如果第一个课程与名称不匹配，则返回-1；从for循环返回。也许您只想在测试完所有课程后返回-1：

for crs in self.myCourses:
    if crs.courseName == course:
        return crs.getGrade()
return -1            

现在for循环只有在找到匹配的进程时才会中断，并且除了"6.00x"之外，您不再返回-1。你知道吗