我正在尝试编写一个通用的例程来从INT返回ENUM [英] I'm trying to write a generic routinue to return ENUM from INT

问题描述

我正在尝试编写一个通用例程，该例程将根据存储在DB中的INT值返回ENUM。



提前致谢

I'm trying to write a generic routine that will return an ENUM based on the INT value stored in the DB.

Thanks in advance

Imports System.ComponentModel
Imports System.Reflection

Public Enum enColour
  <Description("BLUE")> clBlue = 1
  <Description("RED")>  clRed = 2
  <Description("GREEN")> clGreen = 3
End Enum

Public Enum enCarMake
  <Description("Ford")> cmFord = 1
  <Description("Toyota")>  cmToyota = 2
  <Description("Skoda")> cmSkoda = 3
End Enum


Public Sub LoadFromDB 
  Dim myENUMColour AS enColour
  Dim myENUMMake As enCarMake

  With rdrLoadFromTable
    ReturnENUMFromInt(CInt(.Item("Colour")), myENUMColour)
    ReturnENUMFromInt(CInt(.Item("CarMake")), myENUMMake)
  End With
End Sub

Public Sub ReturnENUMFromInt(pIntValueFromDB AS Integer, pReturnValue AS [ENUM])
  'LOOKING FOR HELP HERE...

  pReturnValue = CType(pIntValueFromDB, pReturnValue.GetType) 
End Sub;

推荐答案

创建自己的函数似乎有点过度杀戮为此， Enum.Parse （或 Enum.TryParse ）甚至 CType 电话会为你做这件事。



但是如果你的情况是这样的，你需要一个通用的方法，那么这样的事可能会为你做的伎俩;

It seems a little over-kill to create your own function for doing this, Enum.Parse (or Enum.TryParse) or even a CType call will do this for you.

But if your circumstances are such that you need a generic method for this, then maybe something like this will do the trick for you;

Module Module1

    Public Enum Color
        Red
        Green
        Blue
    End Enum

    Public Enum CarMake
        Ford
        Toyota
        Skoda
    End Enum

    Sub Main()
        Dim color As Color = ToEnum(Of Color)(1)
        Dim carMake as CarMake ToEnum(Of CarMake)(2)
    End Sub

    Public Function ToEnum(Of T As Structure)(ByVal arg As Integer) As T
        If [Enum].IsDefined(GetType(T), arg) Then
            Return [Enum].Parse(GetType(T), arg.ToString())
        Else
            Throw New ArgumentException(String.Format("'{0}' is not defined in enumeration {1}", arg, GetType(T).FullName))
        End If
    End Function
End Module

希望这有帮助，

Fredrik

Hope this helps,
Fredrik

试试 Enum.TryParse [ ^ ]，应该做你想做的事。

Try Enum.TryParse[^], should do what you want.

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