Hi I am working on a project where my class has to execute VB code provided by the user, to make it simple i am trying to recreate my own eval function, i am using the following code i found on the web to do this task
Imports Microsoft.VisualBasic
Imports System
Imports System.Text
Imports System.CodeDom.Compiler
Imports System.Reflection
Imports System.IO
Namespace PAB.Util
Public Class EvalProvider
Public Function VS_Eval(ByVal vbCode As String) As Object
Dim c As VBCodeProvider = New VBCodeProvider
Dim icc As ICodeCompiler = c.CreateCompiler()
Dim cp As CompilerParameters = New CompilerParameters
cp.ReferencedAssemblies.Add("system.dll")
cp.ReferencedAssemblies.Add("system.xml.dll")
cp.ReferencedAssemblies.Add("system.data.dll")
' Sample code for adding your own referenced assemblies
'cp.ReferencedAssemblies.Add("c:\yourProjectDir\bin\YourBaseClass.dll")
'cp.ReferencedAssemblies.Add("YourBaseclass.dll")
cp.CompilerOptions = "/t:library"
cp.GenerateInMemory = True
Dim sb As StringBuilder = New StringBuilder("")
sb.Append("Imports System" & vbCrLf)
sb.Append("Imports System.Xml" & vbCrLf)
sb.Append("Imports System.Data" & vbCrLf)
sb.Append("Imports System.Data.SqlClient" & vbCrLf)
sb.Append("Namespace PAB " & vbCrLf)
sb.Append("Class PABLib " & vbCrLf)
sb.Append("public function EvalCode() as Object " & vbCrLf)
'sb.Append("YourNamespace.YourBaseClass thisObject = New YourNamespace.YourBaseClass()")
sb.Append(vbCode & vbCrLf)
sb.Append("End Function " & vbCrLf)
sb.Append("End Class " & vbCrLf)
sb.Append("End Namespace" & vbCrLf)
Debug.WriteLine(sb.ToString()) ' look at this to debug your eval string
Dim cr As CompilerResults = icc.CompileAssemblyFromSource(cp, sb.ToString())
Dim a As System.Reflection.Assembly = cr.CompiledAssembly
Dim o As Object
Dim mi As MethodInfo
o = a.CreateInstance("PAB.PABLib")
Dim t As Type = o.GetType()
mi = t.GetMethod("EvalCode")开发者_如何学运维
Dim s As Object
s = mi.Invoke(o, Nothing)
Return s
End Function
End Class
End Namespace
The problem with code is that it can't access any variables or there values, so i have decided to get the variable names, there values types and there types dynamically and recreate them in the class that is being created dynamically.
Please suggest a way to get the variable names there types and values in the current class or method, so that i can recreate them, and execute the user passed code, the user knows what variables are in the current class or method and there datatypes but he don't know there values as they may have changed, so he can't initialize them.
Is there a way to do this, this code will be called in an asp.net page on page_load event, the code passed by the user is stored in the variable vbCode that is passed as a parameter.
If there is any other method to do this, please suggest
Thank you
I have finally found the solution of how to get the variables and values of the current instance of a class.
using System.Reflection;
it is very easy to achieve, all you have to write is the following line:
Dim fields As FieldInfo() = Me.GetType().GetFields()
For Each fld As FieldInfo In fields
Dim name As String = fld.Name
Dim value = fld.GetValue(Me)
Dim typ As Type = fld.FieldType
Next
Note : It only works for public variables
This may help you?
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