详解C#如何实现隐式类型转换

namespace TestProject1;
 
public class GetResultTests
{
    [Test]
    public void Test1()
    {
        // 通过 GetResult 方法获取 Result 类型的返回值
        var result = GetResult();
        Assert.Pass();
    }
 
    public Result GetResult()
    {
        if (DateTime.Now.Second > 30)
        {
            // 如果成功，返回 Ok
            return Ok();
        }
        else
        {
            // 如果失败，返回 Error
            return Error();
        }
    }
}

using static System.Math;
 
double x = 3.14;
double y = Sqrt(x);
Console.WriteLine(y); // Outputs 1.77

int[] numbers = { 1, 2, 3, 4, 5 };
int sum = numbers.Sum();
Console.WriteLine(sum); // Outputs 15

global using System.Linq;

int x = 1234;
double y = x;
Console.WriteLine(y); // Outputs 1234

public struct Id
{
    public string Value { get; }
 
    public Id(string value)
    {
        Value = value;
    }
 
    public static implicit operator Id(string value) => new Id(value);
}

Id id = "123";

public readonly struct Result
{
    public Result(bool isSuccess)
    {
        IsSuccess = isSuccess;
    }
 
    public bool IsSuccess { get; }
}

public readonly struct ErrorTag
{
}
 
public readonly struct SuccessTag
{
}

public readonly struct Result
{
    public Result(bool isSuccess)
    {
        IsSuccess = isSuccess;
    }
 
    public bool IsSuccess { get; }
 
    public static implicit operator Result(SuccessTag _) => new Result(true);
    public static implicit operator Result(ErrorTag _) => new Result(false);
}

Result ok = new SuccessTag();
Result error = new ErrorTag();

public static class ResultHelper
{
    public static SuccessTag Ok() => new();
    public static ErrorTag Error() => new();
}

Result ok = ResultHelper.Ok();
Result error = ResultHelper.Error();

global using static ResultHelper;

Result ok = Ok();
Result error = Error();