C# - Generic Method Overloading Compilation Error In VB?
Aug 5, 2009
I have a problem with the VB.NET compiler failing to compile a class (in a separate C# assembly) which contains two overloads of a method with generic arguments. The equivalent code in C# compiles against the same assembly with no errors. Here are the two method signatures:
protected void SetValue<T>(T newValue, ref T oldValue)
protected void SetValue<T>(T? newValue, ref T? oldValue) where T : struct
Here is the code to three assemblies that demonstrate the problem. The first is the C# assembly with a Base class that implements the generic methods. The second is a C# class derived from Base and calls both overloads of SetValue correctly. The third is a VB class also derived from Base, but fails to compile with the following error message:
[Code]...
Am I doing something wrong in the VB code, or are C# & VB different when it comes to generic overload resolution? If I make the method arguments in Base non-generic then everything compiles correctly, but then I have to implement SetValue for every type that I wish to support.
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Oct 7, 2010
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]....
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May 12, 2012
maybe it's not a method exactly. here's what I'd like to do:
Private _Columns As ArrayList
Public Property Columns() As ArrayList
Get[code]....
which would allow me to conveniently set the property by assigning to it various kinds of collection types... except, I can't do it because apparently the Set method has to take an argument of the type of the property itself... I get the complaint:
'Set' parameter must have the same type as the containing property
is there a way to do this?
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Oct 19, 2010
Consider a MyForm class that contains a shadowed implementation of Show(). It also contains a CreateForm() method, which accepts an instance of the form and calls the shadowed sub:
[Code]....
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May 3, 2012
I am having a problem convincing Visual Studio and the compiler to use the correct method overload, possibly because of inheritance.
Given these objects:
Public Class Matrix
...
End Class
[code]....
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Aug 2, 2010
i recently discovered a nice feature called overloading, now the question is can i also do that for outputs? for example i want to call a function that would automatically return the datatype i assign the function toright now im geting an error saying "blabla and blabla cant overload eachother because they only differ by return types
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May 18, 2012
This is a general question about Object Orientation and specifically overloading functions in .NET (or any other framework or language). I am looking at an application that has a lot of duplicate code. For example, have a look at the following functions: [code] I would of thought that best pratice would be to put: //code that is specifically relevant to Test1 variable in a separate function as it is common in both functions.
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Apr 13, 2012
Consider:
Public MustInherit Class Column
Public ReadOnly Property ReturnSomethingUseful() As Object
Get
'return something useful
[code]....
But this gives the following error:
Public Overrides Function ParseValue(sValue As String) As Boolean'
cannot override 'Public Overridable Function ParseValue(sValue As String) As Object'
because they differ by their return types.
I accept that you can't do this, but I'd like to be able to preserve the semantics of what I'm. trying to do, which is to have an untyped version that deals with Object, but a typed version in derived classes that knows about the specific type T.
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Sep 16, 2010
Write an overload for every numeric type or if possible constrain a generic extension method to just numeric types.
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Nov 20, 2009
I have a module with code that refers to controls on form1 form1.textbox1.text 'after adding the sub new overload below to my form my module gives me "reference to a non shared member requires an object reference" why is that? [code]
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Jul 28, 2011
passing a variable to another formI have a module with code that refers to controls on form1form1.textbox1.text 'after adding the sub new overload below to my form my module gives me "reference to a non shared member requires an object reference"
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Dec 19, 2011
I have the following code in C#:
public static ArrayList GetGenders()
{
return new ArrayList()
{
new { Value = 1, Display = "ap" },
new { Value = 2, Display = "up" }
[Code]...
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Oct 12, 2010
I had a code for getting the hdd id written in vb.netNow I need to re-write the code into c#. I have converted the vb.net code to c# but it is not compiling.Below is the vb.net code
Dim hdCollection As ArrayList = New ArrayList()
Dim searcher As ManagementObjectSearcher = New ManagementObjectSearcher("SELECT * FROM Win32_DiskDrive")
[code].....
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Dec 27, 2011
I'm running 64bits Windows 7 and using MS Visual Studio 2010. I'm doing a VB program connecting to mySQL database using 32bits ODBC connection. the program have no issues loading crystal report in Visual Studio IDE environment. However, after Build and install in the same machine the following error msg appeared when trying to load the crystal report with data call from database (ABLE
to display report when NO data call):
See the end of this message for details on invoking
just-in-time (JIT) debugging instead of this dialog box.
[Code].....
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Apr 2, 2009
We were working with a VB.Net app that contains something like 2200 VB modules/forms/classes and got a not-uncommon error message when we went to compile it. (Didn't write down the exact message, but it's basically unable to copy an image file that's in use.)Problem, of course, is that not everybody got out of the app when we told them to. Like I said, not uncommon. (It's a shared app that runs from a server.)Now, the weird thing. After kicking the offenders out, when we recompiled the program the image, which we use on search buttons, was gone. The file was still there but all of the property settings that referenced it were gone. Looked into the Designer code & they were gone from there, too. Seems to me that a compiler should *mark* the code that won't compile, not delete it.Anyway, I only see two courses. Either we restore our app from a backup, losing all our changes, or we go thru all the forms (like I said, there are 2200 modules-not sure how many are forms, but it's a bunch) and manually replace the properties on all the search buttons. Either way it's going to cost us at least a day's work.
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Apr 21, 2011
I am getting the following compilation errors from Microsoft Visual Basic 2010 Express on the first line of my code:
Error 1 Newline in constant C: cdotnetdevsrcvbmain estHelper.vb 1 1 Component Sources
Error 2 Too many characters in character literal C: cdotnetdevsrcvbmainRtestHelper.vb 1 1 Component Sources
The first line of my code is simply:
' Copyright 2011
It is generating the same compilation error for all my comments. Does anyone know why MS VB Express 2010 is acting this weird? Comments in visual basic are supposed to start with a single apostrophe so I don't understand this weird behavior.
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Jul 25, 2011
I'm using access to replicate something that is very simple in excel. I have one "due date" column, and I want the cell right next to those cells to tell me if there are less than 15 days to that date. In excel is a simple conditional function, but I want to do it in Access because it looks better.I'm new to access and even though I've been reading some posts and forums I haven't been able to pull this out. I tried to program a macro with the following
Sub Alarma()
[Alarma] = IIf([Fecha de vencimiento] - 15 > Date(), " ", "Faltan menos de 15 d�as")
[code]....
It shows the following error -> Compilation error: External name not defined.
So, it's not reading the "Alarma" field... how do I define this field? It's inside a formulary, and Alarma is the title (I downloaded a template from the internet and changed the titles so I wouldn't have to do it from scratch...)
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Feb 15, 2010
I keep getting this compilation error code 1 and when I click on swhow compiler detailed output, it shows the following:
[code]...
The aspnet user account has also vanished..
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Oct 4, 2010
We have a Visual Basic Compilation Error at the web site located at [URL] Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.
[Code]...
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Jun 1, 2009
Quote:Value of type System.Nullable(Of Decimal) cannot be converted to System I have the code below which seems to work fine on my development server but causes a compilation error when I put it on my live webserver (uncommented).The error message I get from the event viewer in IIS is as above.
' <WebMethod(Description:="Insert into Referral Payments Table.")> _
'Public Function InsertReferralPayment(ByVal ReffererCustID As Integer, ByVal InstalledCustID As Integer, ByVal AmountReferrer As Nullable(Of Decimal), ByVal AmountInstalled As Nullable(Of Decimal), ByVal ReferrerChequeSentDate As Nullable(Of Date), ByVal InstalledChequeSentDate As Nullable(Of Date), ByVal ReferrerChequeNo As Integer, ByVal InstalledChequeNo As Integer, ByVal InputBy As String) As Integer
[code]....
From what I can tell IIS is configured the same and both referenced DataTables seem identical.
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Apr 28, 2010
I am really trying to follow the DRY principle. I have a sub that looks like this?
Private Sub DoSupplyModel
OutputLine("ITEM SUMMARIES")
Dim ItemSumms As New SupplyModel.ItemSummaries(_currentSupplyModel, _excelRows)
ItemSumms.FillRows()
[Code]...
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Jun 7, 2009
I have a class myClass. MyClass has a property myName. I have a generic list myList(of myClass). I have to check if value of myName in all myClass objects in myList is same and is equal to a string myString. I have created a method:
Private Function IsMatching(ByVal objMyClass As MyClass, ByVal strMyString As String) As Boolean
If objMyClass.MyName = strMyString Then
Return True
Else
Return False
End If
End Function
Now I want to use is TrueForAll method of Generic list. How can I use it ?
If there was No second Parameter in IsMatching method, I could have simply used
myList.TrueForAll(AddressOf IsMatching)
But since there is a parameter strMyString, I dont understand how can I use IsTrueForAll method. How can I use IsTrueForAll method in this scenario.
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Jul 29, 2011
Currently my code has the following properties:
[Code]...
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May 30, 2012
After looking at this thread.>>
How to randomize the alphabet I have decided to make it into an extension method for a String and a List.
Note: Please see the following post if you are still using VB.Net 2002, 2003 or 2005
this code is for use with 2008 and later versions of VB.Net
String.Mix and also List.Mix I was trying to write a generic extension method for every Enumerable(Of T)
I settled on just doing it for a STRING
[Code]...
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Sep 27, 2010
Getting this error message and I am not able to figure out why. Here is my code:
<asp:TextBox ID="searchParam" Width="250px" runat="server"></asp:TextBox><asp:button ID="btnSearch" runat="server" Text="Search" />
<asp:ObjectDataSource ID="ObjectDataSource1" runat="server" SelectMethod="getCOMDLs" TypeName="NewEmployee">
[Code]...
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Jun 19, 2009
I have 3 similar functions, that only change based on numeric type:
<Extension()> _
Public Function ToNullableShort(ByVal str As String) As Short?
Dim intReturn As Short
[Code].....
I was trying to make a generic function out of this, but couldn't do it. How can I make a generic function that will take a specific T and make it a Nullable(of T)?
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Dec 16, 2010
I have a custom list that inherits Generic.List and it has a method for deselecting all of the members named DeselectAll It has looked like this for a few weeks and has worked fine.
Public Sub DeselectAll()
MyBase.ForEach(Function(p As Publipostable) p.ModeEnvoiChoisi = Nothing)
End Sub
Today, it stopped working ?!? I reverted to an earlier version using delegates and that works fine...
Public Sub DeselectAll()
MyBase.ForEach(AddressOf DeselectModeEnvoi)
End Sub
[code]....
Edit: Stopped Working meaning it no longer sets the property p.ModeEnvoiChoisi to Nothing on each item in the list. The DeselectAll method gets called, but all the items retain their previous values...
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Feb 16, 2009
I'm trying to search a generic list of 'User' business objects which has a property called 'Username': If (From u In colUsers Select u.Username Where Username.Equals(strUsername)).Count > 0 ThenI keep getting:Delegate to an instance method cannot have null 'this'.
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Jul 13, 2011
Why does my the declaration of my string in the code result in the following error? Is there a workaround?
Code:
<script runat="server">
Protected Sub form1_Load(sender As Object, e As System.EventArgs)
Dim x As String = "</script>"
[code]....
Error: Statement cannot appear within a method body. End of method assumed.
Note: The following page did not fix my issue and instead resulted in the string </script> being output in my page. ( VB.NET hates </script> tag in string literal )
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Dec 16, 2009
We have migrated our Vb6 application to VB.NET using a third party tool. Now we are in a process of Refactoring and introducing object oriented concepts in the application.
In VB6, we were using structures in many places. As a part of introducing object oriented programming,
1. is it a good idea of changing all Structures to Classes? or Is there a concept of "Generic Structure" similar to Generic collections, Generic classes?
2. Can some one guide me any source containing guide lines or best practices for applications that are migrated to VB.NET from VB6 and implementing object oriented programmaing.
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