C# Record构造函数的行为更改详解

public class StringValidator
{
    public string InputString { get; }


    public StringValidator(string inputString)
    {
        if (string.IsNullOrEmpty(inputString)) throw new ArgumentNullException(nameof(inputString));


        InputString = inputString;
    }
}

    public record StringValidator(string InputString);

public record StringValidator
{
    public string InputString { get;  }


    public StringValidator(string inputString)
    {
        if (string.IsNullOrEmpty(inputString)) throw new ArgumentNullException(nameof(inputString));


        InputString = inputString;
    }
}

using System;


namespace ConsoleApp25
{
    class Program
    {
        static void Main(string[] args)
        {
            //This throws an exception from the constructor
            //var stringValidator = new StringValidator(null);


            var stringValidator1 = new StringValidator("First");
            var stringValidator2 = stringValidator1 with { InputString = "Second" };
            Console.WriteLine(stringValidator2.InputString);


            //This throws an exception from the init accessor
            //var stringValidator3 = stringValidator1 with { InputString = null };


            //Output: Second
        }
    }


    public record StringValidator
    {
        private string inputString;


        public string InputString
        {
            get => inputString;
            init
            {
                //This init accessor works like the set accessor
                ValidateInputString(value);
                inputString = value;
            }
        }


        public StringValidator(string inputString)
        {
            ValidateInputString(inputString);
            InputString = inputString;
        }


        public static void ValidateInputString(string inputString)
        {
            if (string.IsNullOrEmpty(inputString)) throw new ArgumentNullException(nameof(inputString));
        }
    }
}

using System.net;


namespace Urls
{
    public record QueryParameter
    {
        private string? fieldValue;


        public string FieldName { get; init; }
        public string? Value
        {
            get => fieldValue; init
            {
                fieldValue = WEBUtility.UrlDecode(value);
            }
        }


        public QueryParameter(string fieldName, string? value)
        {
            FieldName = fieldName;
            fieldValue = WebUtility.UrlDecode(value);
        }


        public override string ToString()
            => $"{FieldName}{(Value != null ? "=" : "")}{WebUtility.UrlEncode(Value)}";
    }
}