C# 13 - (8) 부분 메서드 정의를 속성 및 인덱서에도 확대

partial 예약어의 지원이,

• C# 2.0 - partial 클래스 지원
• C# 3.0 - partial 메서드 지원
• C# 9.0 - partial 메서드 개선 (반환 타입 허용, out 매개변수 허용, 접근 제한자 허용)

More partial members
; https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-13#more-partial-members

Partial properties ([Proposal]: Partial properties (VS 17.11, .NET 9) #6420)
; https://github.com/dotnet/csharplang/issues/6420

namespace ConsoleApp1;

internal class Program
{
    static void Main(string[] args)
    {
        Device device = new Device { Name = "Device 1" };

        Hub hub = new Hub();
        hub[0] = device;

        Console.WriteLine(hub[0].Name); 
    }
}

public partial class Device
{
    string _name = "";
    public partial string Name { get; set; } // partial 속성 선언
}

public partial class Device
{
    public partial string Name // partial 속성 정의
    {
        get => _name;
        set => _name = value;
    }
}

public partial class Hub
{
    Device[] _devices = new Device[10];

    public partial Device this[int index] { get; set; } // partial 인덱서 선언
}

public partial class Hub
{
    public partial Device this[int index] // partial 인덱서 구현
    {
        get => _devices[index];
        set => _devices[index] = value;
    }
}

// UserCode.cs
public partial class ViewModel : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    [NotifyPropertyChanged]
    public partial string UserName { get; set; }
}

// Generated.cs
public partial class ViewModel
{
    private string __generated_userName;

    public partial string UserName
    {
        get => __generated_userName;
        set
        {
            if (value != __generated_userName)
            {
                __generated_userName = value;
                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(UserName)));
            }
        }
    }
}