vb.net 实现javascript中的Eval功能

　　vb.net中实现javascript中包含的功能，绝对不会有问题。做过javascript开发的程序员对eval都会有深刻的印象。只是在vb.net中实现这个功能没有想象得那么简单。不管怎么说能实现就好。但不知道是否还有其他比较简单的方法。 

　　例子代码如下：

Imports 
   System.CodeDom.Compiler
 
  Public 
    
  Class Form1 
  Class Form1

    Private Sub Button1_Click()Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        　MsgBox(Calculate("1+2*3+4").ToString)
    End Sub

    Public Function Calculate()Function Calculate(ByVal expression As String) As Object
        Dim className As String = "clsF"
        Dim methodName As String = "funCal"

        Dim classSource As New System.Text.StringBuilder

        classSource.Append("public   class   " + className + vbCrLf)
        classSource.Append("         public  function " + methodName + "() as object" + vbCrLf)
        classSource.Append("                 return   " + expression + vbCrLf)
        classSource.Append("         end function" + vbCrLf)
        classSource.Append("end class")

        Dim codeProvider As New VBCodeProvider
        Dim cParams As New CompilerParameters
        cParams.GenerateExecutable = False
        cParams.GenerateInMemory = False
        Dim cResults As CompilerResults = codeProvider.CompileAssemblyFromSource(cParams, classSource.ToString)
        Dim asm As System.Reflection.Assembly = cResults.CompiledAssembly
        Dim eval As Object = asm.CreateInstance(className)
        Dim method As System.Reflection.MethodInfo = eval.GetType().GetMethod(methodName)
        Dim args() As String = Nothing
        Dim reObj As Object = method.Invoke(eval, args)

        GC.Collect()
        Return reObj
    End Function
End Class

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