Runtime Generated EventHandler of Unknown Type - vb.net

Question

Ok, so I have been stuck on this for a while, combining various question solutions from on here.
Situation:
I instantiate an Object of Type x by using the activator.CreateInstance(x)
Type x can vary but always has the same properties and methods.
The problem is that type x has an event ReadCompleted as ReadCompleted (this is a delegate), type y has the same event, with the same delegate but it is of type ReadCompleted1, z => ReadCompleted2, etc...
Solution:
I assign a delegate at runtime using the following code:
Dim Client As Object = ServiceProvider.GetService(TypeDict(Entity))
Dim TaskCompletionSource As New TaskCompletionSource(Of Entity)()
Dim addMethod As MethodInfo = Client.GetType().GetMethod("add_ReadCompleted")
Dim removeMethod As MethodInfo = Client.GetType().GetMethod("remove_ReadCompleted")
Dim self As Object = Nothing
Dim getSelf As Func(Of Object) = Function() self
Dim eventArgType As Type = Client.GetType().GetEvent("ReadCompleted").EventHandlerType.GetMethod("Invoke").GetParameters()(1).ParameterType
Dim e As ParameterExpression = Expression.Variable(eventArgType)
Dim ExpBlock As BlockExpression = Expression.Block({Expression.Parameter(GetType(Object)), e},
Expression.Call(
Nothing,
Me.GetType().GetMethod("ProcessTask"),
Expression.Convert(e, eventArgType),
Expression.Constant(TaskCompletionSource)),
Expression.Call(
Expression.Constant(Client),
removeMethod,
Expression.Convert(
Expression.Invoke(
Expression.Constant(getSelf)),
addMethod.GetParameters()(0).ParameterType)
)
)
Dim lambda As LambdaExpression = Expression.Lambda(
addMethod.GetParameters()(0).ParameterType,
ExpBlock,
Expression.Parameter(GetType(Object)),
Expression.Parameter(eventArgType))
Dim dlg As [Delegate] = lambda.Compile()
self = dlg
addMethod.Invoke(Client, {dlg})
Client.ReadAsync(PrimaryKey)
Now my knowledge on linq and it's Expression class is limited and i did my best to research the msdn documentation but i can't figure it out:
the method ProcessTask gets called properly, for which i've worked long enough, but my parameter e is always Nothing, resulting in a NullReferenceException.
The method:
Public Shared Sub ProcessTask(ByVal e, ByRef tcs)
'Console.WriteLine(e.GetType())
If e.Error IsNot Nothing Then
tcs.TrySetException(e.Error)
ElseIf e.Cancelled Then
tcs.TrySetCanceled()
Else
tcs.TrySetResult(e.Result)
End If
End Sub
I have no idea why, according to how i see it this is the correct way to call my method, but obviously it isn't. Can someone point me in the right direction for this?
Could be I'm just plain blind and missing something very obvious....
Thanks in advance!
EDIT:
Whilst awaiting an answer i tried to do some more debugging(which is hell in this scenario) saw that if i do:
Dim s As ParameterExpression = Expression.Variable(GetType(Object), "Sender")
Dim ExpBlock As BlockExpression = Expression.Block({s, e},
Expression.Call(
Nothing,
GetType(Console).GetMethod("WriteLine", New Type() {GetType(String)}),
Expression.Call(s, GetType(Object).GetMethod("ToString"))),
Expression.Call(
Expression.Constant(Client),
removeMethod,
Expression.Convert(
Expression.Invoke(
Expression.Constant(getSelf)),
addMethod.GetParameters()(0).ParameterType)
))
The sender as object parameter is also nothing, so i'm getting the feeling that none of my arguments are getting passed through...
Hope this helps shed more light on the matter.

Answer 1

I figured it out, turns out i misinterpreted the whole parameter thing of Expression:
Dim Client As Object = ServiceProvider.GetService(TypeDict(Entity))
Dim TaskCompletionSource As New TaskCompletionSource(Of Entity)()
Dim addMethod As MethodInfo = Client.GetType().GetMethod("add_ReadCompleted")
Dim removeMethod As MethodInfo = Client.GetType().GetMethod("remove_ReadCompleted")
Dim self As Object = Nothing
Dim getSelf As Func(Of Object) = Function() self
Dim eventArgType As Type = Client.GetType().GetEvent("ReadCompleted").EventHandlerType.GetMethod("Invoke").GetParameters()(1).ParameterType
Dim s As ParameterExpression = Expression.Parameter(GetType(Object), "Sender")
Dim e As ParameterExpression = Expression.Variable(eventArgType, "EventArgs")
Dim ExpBlock As BlockExpression = Expression.Block(\*{Expression.Parameter('GetType(Object)), e},*\ <--- this has to go
Expression.Call(
Nothing,
Me.GetType().GetMethod("ProcessTask"),
Expression.Convert(e, eventArgType),
Expression.Constant(TaskCompletionSource)),
Expression.Call(
Expression.Constant(Client),
removeMethod,
Expression.Convert(
Expression.Invoke(
Expression.Constant(getSelf)),
addMethod.GetParameters()(0).ParameterType)
)
)
Dim lambda As LambdaExpression = Expression.Lambda(
addMethod.GetParameters()(0).ParameterType,
ExpBlock,
s,
e)
\*Expression.Parameter(GetType(Object)),
Expression.Parameter(eventArgType))*\ <-- this has to change
Dim dlg As [Delegate] = lambda.Compile()
self = dlg
addMethod.Invoke(Client, {dlg})
Client.ReadAsync(PrimaryKey)
So as i see it the parameters don't have to be defined in the expression itself, but they sould be created, and the reference should be kept to use them in the lambda in which you compile the expression.
Hope someone in the future has some use for this answer, and thanks to all for taking a look at this.