Create Class dynamically at runtime

孤街醉人 提交于 2019-11-30 10:15:23
Vahid Farahmandian

I finally succeeded in doing it. My Code is as:

 Public Shared Function CreateClass(ByVal className As String, ByVal properties As Dictionary(Of String, Type)) As Type

    Dim myDomain As AppDomain = AppDomain.CurrentDomain
    Dim myAsmName As New AssemblyName("MyAssembly")
    Dim myAssembly As AssemblyBuilder = myDomain.DefineDynamicAssembly(myAsmName, AssemblyBuilderAccess.Run)

    Dim myModule As ModuleBuilder = myAssembly.DefineDynamicModule("MyModule")

    Dim myType As TypeBuilder = myModule.DefineType(className, TypeAttributes.Public)

    myType.DefineDefaultConstructor(MethodAttributes.Public)

    For Each o In properties

        Dim prop As PropertyBuilder = myType.DefineProperty(o.Key, PropertyAttributes.HasDefault, o.Value, Nothing)

        Dim field As FieldBuilder = myType.DefineField("_" + o.Key, o.Value, FieldAttributes.[Private])

        Dim getter As MethodBuilder = myType.DefineMethod("get_" + o.Key, MethodAttributes.[Public] Or MethodAttributes.SpecialName Or MethodAttributes.HideBySig, o.Value, Type.EmptyTypes)
        Dim getterIL As ILGenerator = getter.GetILGenerator()
        getterIL.Emit(OpCodes.Ldarg_0)
        getterIL.Emit(OpCodes.Ldfld, field)
        getterIL.Emit(OpCodes.Ret)

        Dim setter As MethodBuilder = myType.DefineMethod("set_" + o.Key, MethodAttributes.[Public] Or MethodAttributes.SpecialName Or MethodAttributes.HideBySig, Nothing, New Type() {o.Value})
        Dim setterIL As ILGenerator = setter.GetILGenerator()
        setterIL.Emit(OpCodes.Ldarg_0)
        setterIL.Emit(OpCodes.Ldarg_1)
        setterIL.Emit(OpCodes.Stfld, field)
        setterIL.Emit(OpCodes.Ret)

        prop.SetGetMethod(getter)
        prop.SetSetMethod(setter)

    Next

    Return myType.CreateType()

End Function

The return value of the function is a Type of my Custom Class.

Jacek_D73

There seems to be a bug. I think this line:

Dim field As FieldBuilder = myType.DefineField("_" + o.Key, GetType(Integer), FieldAttributes.[Private])

should look like this:

Dim field As FieldBuilder = myType.DefineField("_" + o.Key, o.Value, FieldAttributes.[Private])

Regards.

A much simpler way is to use the System.Activator:

Activator.CreateInstance(YourType, ParramArrayOfYourVariablesForNEW)

So say I have a class (Test) that takes a single string in the initialization

Public Class Test
    Public Sub New(byval MyString as string)
...

You could create a new instance like this:

Activator.CreateInstance(gettype(Test),"My String")
Lunadix

This line:

Dim field As FieldBuilder = myType.DefineField("_" + o.Key, GetType(Integer), FieldAttributes.[Private])

must to be replaced with this:

Dim field As FieldBuilder = myType.DefineField("_" + o.Key, o.Value, FieldAttributes.[Private])
易学教程内所有资源均来自网络或用户发布的内容,如有违反法律规定的内容欢迎反馈
该文章没有解决你所遇到的问题?点击提问,说说你的问题,让更多的人一起探讨吧!