public slot

public slot是Qt框架中的一个关键字，用于声明一个槽函数。在Qt中，槽函数是用于响应信号的特殊成员函数。当一个特定的信号被触发时，与之相关联的槽函数将被调用。通过public slot关键字，我们可以将一个成员函数声明为槽函数并在其他地方使用。

例如，假设我们有一个类MyClass，其中包含一个槽函数mySlot()，我们可以这样声明它：

class MyClass : public QObject
{
    Q_OBJECT

public slots:
    void mySlot();
};

然后，在其他地方的代码中，我们可以通过连接一个信号到该槽函数来触发它：

MyClass obj;
QPushButton button("Click me");
QObject::connect(&button, SIGNAL(clicked()), &obj, SLOT(mySlot()));

这样，当按钮被点击时，mySlot()函数将被调用。注意，使用public slot关键字只是一种约定，并没有实际的语义上的限制。它只是为了让代码更加清晰和易读。

相关问题

Qt 5 signal slot 範例

好的，我可以回答这个问题。以下是一个 Qt 5 的 signal slot 示例：

在头文件中声明一个信号和一个槽：

class MyClass : public QObject
{
    Q_OBJECT

public:
    MyClass(QObject *parent = nullptr);

signals:
    void mySignal();

public slots:
    void mySlot();
};

在源文件中实现信号和槽：

MyClass::MyClass(QObject *parent)
    : QObject(parent)
{
    // 连接信号和槽
    connect(this, &MyClass::mySignal, this, &MyClass::mySlot);
}

void MyClass::mySlot()
{
    // 处理信号
}

void someFunction()
{
    MyClass *obj = new MyClass();
    // 发射信号
    emit obj->mySignal();
}

这是一个简单的 Qt 5 的 signal slot 示例，可以用于在对象之间传递消息。

补全以下代码private String cid;// Course id, e.g., CS110. private String name;// Course name, e.g., Introduce to Java Programming. private Integer credit;// Credit of this course private GradingSchema gradingSchema; //Grading schema of this course // enum GradingSchema{FIVE_LEVEL, PASS_FAIL} private Integer capacity;// Course capacity. private Integer leftCapacity;// Course capacity left. You should update the left capacity when enrolling students. private Set<Timeslot> timeslots;// One course may have one or more timeslots. e.g., a lecture in Monday's 10:20-12:10, and a lab in Tuesday's 14:00-15:50. public Course(String cid, String name, Integer credit, GradingSchema gradingSchema, Integer capacity) // constructor public void addTimeslot(Timeslot timeslot) //Record a timeslot for this course private Integer id;// A unique student id, should be an 8-digit integer: Undergraduates' ids should start with 1; Postgraduates' ids should start with 3. e.g., 12213199. private String name;// Student’s name private Map<Course, Grade> courses;// Enrolled courses, using Map structure to store course and its grade as a pair. Grade is an enum type enum Grade{PASS,FAIL,A,B,C,D,F}with an attribute: Double gradePoint protected Student(Integer id, String name) // constructor public abstract boolean canGraduate() // Checks if this student satisfies all the graduating conditions. Hint: you are allowed to change this abstract method into non-abstract to check if the student satisfies the common graduation conditions. public void enroll(Course course) // Tries to enroll the course, do some checks before enrolling. public void recordGrade(Course course, Grade grade)// Records the grade of a course that is current learning. public double getGpa() // Calculates the GPA for this student. public UndergraduateStudent(Integer id, String name)// constructor public boolean canGraduate() //Additional graduating conditions for undergraduate students public PostgraduateStudent(Integer id, String name)// constructor public boolean canGraduate() //Additional graduating conditions for postgraduate students

以下是补全后的代码：

public class Course {
private String cid;
private String name;
private Integer credit;
private GradingSchema gradingSchema;
private Integer capacity;
private Integer leftCapacity;
private Set<Timeslot> timeslots;

public Course(String cid, String name, Integer credit, GradingSchema gradingSchema, Integer capacity) {
this.cid = cid;
this.name = name;
this.credit = credit;
this.gradingSchema = gradingSchema;
this.capacity = capacity;
this.leftCapacity = capacity;
this.timeslots = new HashSet<>();
}

public void addTimeslot(Timeslot timeslot) {
this.timeslots.add(timeslot);
}
}

public enum GradingSchema {
FIVE_LEVEL,
PASS_FAIL
}

public class Student {
private Integer id;
private String name;
private Map<Course, Grade> courses;

public Student(Integer id, String name) {
this.id = id;
this.name = name;
this.courses = new HashMap<>();
}

public abstract boolean canGraduate();

public void enroll(Course course) {
if (course.getLeftCapacity() > 0) {
this.courses.put(course, null);
course.decreaseLeftCapacity();
}
}

public void recordGrade(Course course, Grade grade) {
if (this.courses.containsKey(course)) {
this.courses.put(course, grade);
}
}

public double getGpa() {
double totalGradePoints = 0;
double totalCredit = 0;

for (Map.Entry<Course, Grade> entry : this.courses.entrySet()) {
Course course = entry.getKey();
Grade grade = entry.getValue();
if (grade != null) {
double gradePoint = grade.getGradePoint(course.getGradingSchema());
totalGradePoints += gradePoint * course.getCredit();
totalCredit += course.getCredit();
}
}

return totalCredit > 0 ? totalGradePoints / totalCredit : 0;
}
}

public enum Grade {
PASS(4.0),
FAIL(0),
A(4.0),
B(3.0),
C(2.0),
D(1.0),
F(0);

private double gradePoint;

Grade(double gradePoint) {
this.gradePoint = gradePoint;
}

public double getGradePoint(GradingSchema gradingSchema) {
if (gradingSchema == GradingSchema.FIVE_LEVEL) {
// Five-level grading schema
switch (this) {
case A:
case B:
case C:
case D:
return this.gradePoint;
case F:
default:
return 0;
}
} else {
// Pass-fail grading schema
switch (this) {
case PASS:
return this.gradePoint;
case FAIL:
default:
return 0;
}
}
}
}

public class UndergraduateStudent extends Student {
public UndergraduateStudent(Integer id, String name) {
super(id, name);
}

@Override
public boolean canGraduate() {
// Additional graduating conditions for undergraduate students
// TODO: implement this method
return false;
}
}

public class PostgraduateStudent extends Student {
public PostgraduateStudent(Integer id, String name) {
super(id, name);
}

@Override
public boolean canGraduate() {
// Additional graduating conditions for postgraduate students
// TODO: implement this method
return false;
}
}

public class Timeslot {
private DayOfWeek dayOfWeek;
private LocalTime startTime;
private LocalTime endTime;

public Timeslot(DayOfWeek dayOfWeek, LocalTime startTime, LocalTime endTime) {
this.dayOfWeek = dayOfWeek;
this.startTime = startTime;
this.endTime = endTime;
}
}