Using VB.NET, is there a way to pass a reference argument when invoking a function in a dll.
Suppose I want to pass arg2 as a reference argument, how would I do that?
method.Invoke(obj, New [Object]() {arg1, arg2, arg3})
In other words I want to point arg2 to something else within the invoked function.
I have a COM component that I want to call using late-binding from VB.NET (using Primary Interop Assembly - PIA method). My IDL signature for the COM method looks like:
HRESULT Send([in]BSTR bstrRequestData,
[out]VARIANT *pvbstrResponseData,
[out]VARIANT *pvnExtCompCode,
[out,retval]int *pnCompletionCode);
So 2 'ByRef' parameters in VB.NET lingo, and a return value. I attempt to invoke this method like so:
Dim parameters(2) As Object
parameters(0) = "data"
parameters(1) = New Object()
parameters(2) = New Object()
Dim p As New ParameterModifier(3)
[Code] .....
This fails spectactularly with an exception: {"Invalid callee. (Exception from HRESULT: 0x80020010 (DISP_E_BADCALLEE))"}
I assume this means I'm doing something wrong in my parameterMods array. Because if I comment out setting any value of the ParameterMods array to 'True' - it works. It of course doesnt update the parameters that are [out] parameters and so it's not working as intended. Is there something else to consider since the method also has a return value? The MSDN example pretty much does exactly what I am doing, with the exception that example did not have a return value.
I'm currently invoking a function that takes ByRef parameters using Control.Invoke (which I notice specifies the Object parameter array to be ByVal) but the array of parameters I give it isn't updated by the function. Is this possible with VB.Net 2003 or must there be some error in my code?
View 5 RepliesI will need to convert the following VB Form code to WPF C#:
// VB Me.Invoke(New FooDelegate(AddressOf Foo), New Object() {cmd})
Where Foo is just a method taking a string argument cmd.
I tried all the following in WPF C#, but all giving me exception:
//C#
dispatcher.Invoke(new FooDelegate(Foo()), cmd);
dispatcher.Invoke(new FooDelegate(Foo(cmd)), cmd);
dispatcher.Invoke(new FooDelegate(Foo()), new object() {cmd});
What is the correct formatting?
I have code, shown below, that works all except for 1 thing: The variables being passed byRef get passed, but once modified in the else section of the "if me.invokerequired" code of RecordData, the variables are never updated in the calling function. To reiterate, the calling function does not receive the updated data that is in the variables custid and amt.When debugging, I see the data change in the else section of "if me.invokerequired", but once it returns from the callback the data is missing.[code]
View 15 RepliesI have a C# interface defined as so:
public interface IMenuSecurityService
{
void SetSecurityFlags(List<MenuItem> items);
}
I need to implement this interface in a VB.Net class. When I implement the SetSecurityFlags method with the items parameter passed ByVal, it compiles.
Public Sub SetSecurityFlags(ByVal items As List(Of L1.Common.Model.MenuItem)) Implements IMenuSecurityService.SetSecurityFlags
' do some work
End Sub
When I try to implement it with the items parameter passed ByRef, I get the following compiler error: Class 'UserRights' must implement 'Sub SetSecurityFlags(items As System.Collections.Generic.List(Of Model.MenuItem))' for interface
Public Sub SetSecurityFlags(ByRef items As List(Of L1.Common.Model.MenuItem)) Implements IMenuSecurityService.SetSecurityFlags
' do some work
End Sub
I can't seem to figure this one out. Does VB.Net not support this or am I doing something wrong?
Switching Byref to Byval on method calls I have many warnings raised due to: "Implicit conversion from xxxx to yyyy in copying the value of 'ByRef' parameter zzzz back to the matching argument."
My feeling is that it would be safe to change the function parameters from byref to byval as nothing special is being done with the reference type pointers inside these methods the reference types are simply being used and I think the behaviour would be exactly the same if running with a copy a pointer rather than the original.
Another consideration is that I have two classes which inherit from a base class. The same situation is occuring in that the byref params are causing implicit casting from the base class to the narrower concrete class. Again I can't see any problems with this code running byval either.Does anyone have any tips regarding use of parameters in functions when dealing with reference types?
Some of the other things that are currently being passed around byref in my project are database connection objects i.e. OracleConnection and SqlConnection. Is there any good reason for passing these around byref?
[Code]...
Public Class StateObject
Public workSocket As Socket = Nothing
Public Const BufferSize As Integer = 1024
Public buffer(BufferSize) As Byte
[CODE]....
I have been using a pretty slick generic invoke method for UI updating from background threads. I forget where I copied it from (converted it to VB.NET from C#), but here it is: Public Sub InvokeControl(Of T As Control)(ByVal Control As t, ByVal Action As Action(Of t))
[Code]....
1. On the main form a scanner class is instantiated that (in the scanner's constructor) sets the scanner settings (baud rate, parity, etc) and opens the scanner for use
2. A barcode is scanned (via a scanner connected to the device in a seral port) while on the main form
3. In the scanner class, the DataRecieved event gets the needed info from the scanned code.
4. Then that info is passed back to the main form to a method RunCommandCode (which takes the scanned info as an argument)
5. On the main form the RunCommandCode calls another method CommandCodeHandler, passing the scanned info again
6. In the CommandCodeHandler sub a method is called in a Utils class (SetSelectedTab), which interacts with the form itself (determines how many tabs exist on a tab control), which is the reason for the invoke in the first place
So, before I figured out I needed to use the Invoke method (and, more specifically, that the scanner was working in a different thread), I was getting an error in step 6 on the line that got the TabControl.TabPages.Count.
[code]...
I am implementing a custom iDispatchLLInvoke handler for VB.NET - some of this is working.So Far - I have been able to intercept and provide custom handling of simple functions and property calls - but I am stuck when I try to set a property and get an error "Invalid Pointer (Exception from HRESULT: 0x80004003 (E_Pointer))".
I am using the new .NET 4.0 ICustomQueryInterface to do this. In Summary - I intercept and provide my own implementation of iDispatch - I load the dispIDs on the first call - and return a the dispID for each call within GetIDsOfNames - this ID is than passed to Invoke where reflection is used to get the value and return the result.
When I attempt to set a property - a call is made to GetIDsofNames and I return a valid dispID - the application than crashes with the error above and no call is made to Invoke.As a result - I am assuming that the issue relates to my interface definition been wrong becase the code never get's back to .NET code - see below for this code:
<ComImport(), Guid("00020400-0000-0000-C000-000000000046"), InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)> _
Public Interface IDispatch
Sub GetTypeInfoCount(ByRef pctInfo
As UInt32)
[code]....
I've created a MyFunc extension (in Module Extensions) for all the base types as well as generic arrays, ICollection(Of T) and Dictionary(Of String,T):
Function MyFunc(Of T)(a() As T) As String
Function MyFunc(Of T)(collection As ICollection(Of T)) As String
Function MyFunc(Of T)(dict As Dictionary(Of String,T)) As String
[code].....
I want to invoke a method on a class that i have a reference to. The method that I want to call has a custom attributes. Currently I can find this attributes and call the property of my class Attribute.
is there a way to invoke that method ?
PS/ The project is written in vbnet, but I think the solution is the same in c#.
I'm trying to make this code with reflection since I want it to manage Technician and other types too.
[Code]....
I have some code in c#
BeginInvoke(new MethodInvoker( delegate() {myAppMethod_Tick(sender, e); }));
Now, When I tried to convert that code to vb.net I have below..
BeginInvoke(New MethodInvoker(Function() Do myAppMethod_Tick(sender, e) End Function))
But it does not compile.. What's problem for it?
Because my c# application works ok without any problem..
Is it possible to somehow invoke foo("SomeAwesomeString") from VBScript directly (i.e., without it having to launch an additional process)?
The use case is this: I am trying to write an 'extension' application for hMailServer (hMS), but hMS can only invoke VBscript scripts when an event happened. I can have the VBscript launch an .exe every time the event happened, but the processing involve opening and closing a connection to a back-end database. So, every invocation is very expensive. I had been thinking that I can reduce the expense by having a Service to maintain the connection (i.e., opening it once and re-open it if the connection closed). Plus by implementing the processing as background worker threads will result in a non-blocking processing + less process-starting overhead.
This is the code i have so far (no i didn't write it all by my self took help from net) but i am unable to understand why i am getting this error
Imports CookComputing.XmlRpc
Public Structure blogInfo
Public title As String
[code]....
error i get is "Invoke on Non-Existent or Non-public proxy method"
Attempting to invoke a method of an interface, of which the return type is _variant_t
Code:
_variant_t resultsDataString;
_bstr_t simObjectNames;
simObjectNames = SysAllocString (L"TEST example 3");
resultsDataString = pis8->GetSimObject (simObjectNames);
[code].....
I Have a Function on my frmMain Class wich will update my control to something else after an invoke. When i type "?Label1.Text" on the Immediate Window, the text property IS updated, but when i go check the Form, nothing happened. The code is just like this
[Code]...
I have a method written in VB.NET. It looks like this:
Shared Sub SomeMethod(ByVal Id As Guid,
Optional ByVal str1 As String = "foo",
Optional ByVal str2 As String = "")
I want to call this method from C# 3.0 and I want it to use its default arguments. I tried passing System.Reflection.Missing.Value, but I cannot cast it as String. Is there any way to do that?
I have a ASP.NET (C#) web page which utilizes a VB class library. The VB library performs a SOAP POST to a remote web service and returns a message. However the VB library keeps running into a "No connection could be made because the target machine actively refused it xxx.xxx.xxx.xxx" However, I've also created a C# test client which consumes the same VB class library and can perform the post just fine! [code]
View 1 RepliesIn C#, python and/or VB.net, how can write a method of a class that can accept different sequences of arguments? As an indication, the multiple choices of arguments sequence would be accessible when pressing shift+shift+space in visual studio.
View 5 RepliesI've got the following code:
[code]...
The problem is that, when I call the "SetStatusBarText" sub from another thread, InvokeRequired is True (as it should be), but then my threads stall on the Me.Invoke statement - pausing execution shows them all just sitting there, not actually invoking anything.
I getting above error at Line: 376.
MichealeLine 374: Dim thisMemberUPID As String=objDataReader("MembershipID")
Line 375: Dim urlName As String = objDataReader("GivenName")
Line 376:
[code]....
Is it possible to pass multiple arguments to a delegate method from a list(Of T).ForEach call?So, I'd like to pass a listbox object to the delegate routine below:
Sub test()
Dim names As New List(Of String)
names.Add("Bruce")
names.Add("Alfred")
[code]....
I've run into a bit of a problem.. I am unsure as to how many people know how "IRC" Servers work here but basically, i'll explain. We are re-creating an IRC Client we made for our Chat site in VB.NET originally vb6. We have serveral different forms but the main problme we are having at the moment is FrmMain is where you login to the servers, it grabs your data from our MySQL database such as "Nick, Gender, Font" etc. Then proceeds with connection to IRC server on Raw 001 we know the connection to the IRC server has been established... so therefore we open up FrmAuth which in this case they can see roomlist etc. We are unable to get FrmAuth to load probably.
We originally had this working opening up FrmAuth before the connection to IRC server has been established.. This really is no good for us causes alot of errors etc. So when we use just simply "me.show()" the form loads but freezes we tried doing Me.Invoke(New Del(AddressOf me.show))
however, this didnt work in which I assume that is because the "FrmAuth" hasn't yet loaded the GUI thread therefore there is no Thread to invoke so we tried FrmMain.Invoke(New Del(AddressOf me.show))
This didn't work either i assume you cannot access another forms Invoke method?
we are receiving the error A first chance exception of type.'System.InvalidOperationException' occurred in System.Windows.Forms.dll which i assume has something to do with it but not quite sure..
So my question comes down to the fact of, how do we open up FrmAuth without it freezing? Is there a way to access the invoke method on another form?
I have a C++ method with this signature:
[Code]...
We are re-creating an IRC Client we made for our Chat site in VB.NET originally vb6
We have serveral different forms but the main problme we are having at the moment is
FrmMain is where you login to the servers, it grabs your data from our MySQL database such as "Nick, Gender, Font" etc. Then proceeds with connection to IRC server on Raw 001 we know the connection to the IRC server has been established... so therefore we open up FrmAuth which in this case they can see roomlist etc. We are unable to get FrmAuth to load probably.
We originally had this working opening up FrmAuth before the connection to IRC server has been established.. This really is no good for us causes alot of errors etc.
So when we use just simply "me.show()" the form loads but freezes we tried doing
Me.Invoke(New Del(AddressOf me.show))
however, this didnt work in which I assume that is because the "FrmAuth" hasn't yet loaded the GUI thread therefore there is no Thread to invoke so we tried
FrmMain.Invoke(New Del(AddressOf me.show)) This didn't work either i assume you cannot access another forms Invoke method..?? we are receiving the error A first chance exception of type 'System.InvalidOperationException' occurred in System.Windows.Forms.dll which i assume has something to do with it but not quite sure..
So my question comes down to the fact of, how do we open up FrmAuth without it freezing? Is there a way to access the invoke method on another form?
I have a filesystewatcher object. On it`s event it runs a procedure which fills a treeview with a data. I had problems with treeview methods, but when I run them using invoke method everything is ok. But I still have one problem. When I load the form for the first time, everything works fine. But, when I then close the form (me.dispose, me.close), and load it once again, when Filesystemwathcer start the procedure i have an exception "invoke or begininvoke cannot be called on a control until the window handle has been created" trying to run a treeview.invoke method?
View 9 RepliesWhat is Platform Invoke Service (P/Invoke)?
View 1 Replies