C# 中的属性

属性通过属性访问器访问，即get;set;方法

语法

• 没有显示声明get;set;方法

public class Person
{
    public string FirstName;
    // 没有显示声明get;set;方法
}

• 显示声明get;set;

public class Person
{
    public string FirstName { get; set; }

}

• 给属性一个默认值,对于只读属性有最大作用

public class Person
{
    public string FirstName { get; private set; } = "zhangsan";

}

• 自定义存储，即声明一个field控制属性赋值读取

public class Person
{
    public string FirstName
    {
        get { return firstName; }
        set { firstName = value; }
    }
    private string firstName;

}

• 升级一下使用lamda表达式

public class Person
{
    public string FirstName
    {
        get => firstName;
        set => firstName = value;
    }
    private string firstName;

}

• 限制只在构造函数初始化属性

public class Person
{
    public Person(string firstName) => this.FirstName = firstName;

    public string FirstName { get; }

}

• 计算属性

public class Person
{
    public string FirstName { get; set; }

    public string LastName { get; set; }

    public string FullName => $"{FirstName} {LastName}";
}

• 缓存计算属性

public class Person
{
    private string firstName;
    public string FirstName
    {
        get => firstName;
        set
        {
            firstName = value;
            fullName = null;
        }
    }

    private string lastName;
    public string LastName
    {
        get => lastName;
        set
        {
            lastName = value;
            fullName = null;
        }
    }

    private string fullName;
    public string FullName
    {
        get
        {
            if (fullName == null)
                fullName = $"{FirstName} {LastName}";
            return fullName;
        }
    }
}

• 不被序列化

public class Person
{
    public string FirstName { get; set; }

    public string LastName { get; set; }

    [field:NonSerialized]
    public int Id { get; set; }

    public string FullName => $"{FirstName} {LastName}";
}

• 观察者模式

public class Person : INotifyPropertyChanged
{
    public string FirstName
    {
        get => firstName;
        set
        {
            if (string.IsNullOrWhiteSpace(value))
                throw new ArgumentException("First name must not be blank");
            if (value != firstName)
            {
                firstName = value;
                PropertyChanged?.Invoke(this,
                    new PropertyChangedEventArgs(nameof(FirstName)));
            }
        }
    }
    private string firstName;

    public event PropertyChangedEventHandler PropertyChanged;
    // remaining implementation removed from listing
}

参考：https://docs.microsoft.com/zh-cn/dotnet/csharp/properties