动态语言运行时

1namespace DynamicLanguageRuntime;
2
3public class Course
4{
5    public string Title { get; set; } = string.Empty;
6}

1using DynamicLanguageRuntime;
2
3var course = new Course() { Title = ".NET Fundamentals" };
4
5// Duration property does not exist
6// We will get an error during compilation
7Console.WriteLine(course.Duration);

为动态演示复用的原始 Course 类

1namespace DynamicLanguageRuntime;
2
3public class Course
4{
5    public string Title { get; set; } = string.Empty;
6}

1using DynamicLanguageRuntime;
2
3// We declare the variable using the dynamic keyword
4dynamic course = new Course() { Title = ".NET Fundamentals" };
5
6// Program compiles and runs because there is no compile-time checking
7// for dynamic objects
8Console.WriteLine("Program started running...");
9
10// However, because there is no Duration property, 
11// the program fails during runtime
12Console.WriteLine(course.Duration);

1// We assign an int value in the beginning
2dynamic someVariable = 24;
3
4Console.WriteLine($"Type of someVariable: {someVariable.GetType()}, value: {someVariable}.");
5
6// Can assign string
7someVariable = "Now, it's a string";
8
9Console.WriteLine($"Type of someVariable: {someVariable.GetType()}, value: {someVariable}.");

1namespace DynamicLanguageRuntime;
2
3public class Course
4{
5    public string Title { get; set; } = string.Empty;
6    public dynamic Duration { get; set; }
7}

1using DynamicLanguageRuntime;
2
3var course = new Course() { Title = ".NET Fundamentals" };
4
5// We set the value of the Duration property to an int object first
6course.Duration = 8; // 8 weeks
7Console.WriteLine($"Duration property type: {course.Duration.GetType()}, value: {course.Duration}.");
8
9// Now we set the value to a string object
10course.Duration = "8 weeks";
11Console.WriteLine($"Duration property type: {course.Duration.GetType()}, value: {course.Duration}.");

1namespace DynamicLanguageRuntime;
2
3public class Course
4{
5    public string Title { get; set; } = string.Empty;
6
7    public int DurationInWeeks { get; set; }
8
9    // The method has dynamic return type
10    public dynamic GetCourseDuration(string format)
11    {
12        // Depending on the value of format,
13        // the return type will either be int or string
14        if (format == "string")
15        {
16            return $"{DurationInWeeks} weeks";
17        }
18        else if (format == "int")
19        {
20            return DurationInWeeks;
21        }
22        else
23        {
24            return "Invalid format provided.";
25        }
26    }
27}

1using DynamicLanguageRuntime;
2
3var course = new Course() { Title = ".NET Fundamentals", DurationInWeeks = 8 };
4
5// GetCourseDuration has the dynamic return type
6dynamic duration = course.GetCourseDuration("string");
7Console.WriteLine($"Type: {duration.GetType()}, value: {duration}");
8
9duration = course.GetCourseDuration("int");
10Console.WriteLine($"Type: {duration.GetType()}, value: {duration}");

1using System.Text.Json.Nodes;
2
3string jsonString = """{ "Name": "Alice", "Role": "Engineer" }""";
4
5// Parse the JSON string into a dynamic node
6dynamic user = JsonNode.Parse(jsonString);
7
8// Use indexers to access dynamic JSON properties
9Console.WriteLine($"User: {user["Name"]}, Role: {user["Role"]}");