c# - 使用结构字段作为参数

Question

我有这门课。

public class EmailManager
{
   public struct AttachmentFormats
   {
        public const string Excel = ".xlsx";        
        public const string Pdf = ".pdf";
   }
   private static bool SendEmail(string to, string from, ???)
   {
      /*??? is one of the AttachmentFormats*/
   }
}

当用户想要使用 SendEmail 时，我想限制他们只使用一种已定义的 AttachmentFormats。喜欢

EmailManager.SendEmail("xxx","yy",EmailManager.AttachmentFormats.Excel);

这可能吗？如果是，我应该怎么做。

Answer 1

你需要 enum 而不是 struct :

public enum AttachmentFormat
{
     xlsx = 0,
     pdf = 1
}

public class EmailManager
{

   private static bool SendEmail(string to, string @from, AttachmentFormat format)
   {
      switch(format)
      {
          case AttachmentFormat.pdf: 
          // logic 
          break;
          case AttachmentFormat.xlsx: 
          // logic 
          break;
      }
   }
}

其他解决方案是创建接口(interface)和实现该接口(interface)的类:

public interface IAttachmentFormat {}

public sealed class PDFAttachmentFormat : IAttachmentFormat { } 
public sealed class XLSXAttachmentFormat : IAttachmentFormat { } 

然后检查 SendEmail 方法中的类型:

   private static bool SendEmail(string to, string @from, IAttachmentFormat format)
   {
      if(format is PDFAttachmentFormat) // some logic for pdf
      if(format is XLSXAttachmentFormat) // some logic for xlsx
   }