using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace FileService.Domain.ValueObjects { public class FileName { public string Value { get; } public FileName(string value) { if(value.Length > 20) { throw new ArgumentException("文件名超出长度"); } Value = value; } public override string ToString() { return Value; } public static implicit operator FileName(string value) { return new FileName(value); } } }