I was familiar with the optional parameters in vb 6 and it made sense given the capabilities of the language but why the heck does VB.Net support optional parameters when there is method overloading? Which one should I use and is there a difference? If there is a difference when should I use each one?
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What are the behaviors difference for the Previous Property of Other1 and Other2 Class.Note than the return type of the ovrloaded Previous Property of Other2 as bean changed to Other2 while it stay as Base for Other1.
Public Class Base
Private _Previous as Base
Protected Overridable ReadOnly Property Previous As Base
[code]....
Coming from C#..I was looking at this website [URL]..And noticed that it said
public static void Main(string[] args) {is equivalent to Overloads Shared Sub Main(ByVal args() As String)
what is that "Overloads" all about?
Do you really need this keyword to overload methods? What is the difference between using the overloads keyword vs. just having different method signatures?
View 5 RepliesHowever, I am wondering if there are any workarounds or plans for incorporating this feature into VB.NET in the future?What I'd like to do:
Public Delegate Function Deserializer(Of T)(ByRef Buffer() As Byte, optional ByRef BufferPosition As Integer = 0) As T
'Implementation of a func that matches the delegate'
Class A
Public Function Deserialize(Byref Buffer() as Byte, optional Byref BufferPosition as integer = 0)
....
In the absence of specifying "optional" inside the actual delegate itself, it'd at least be nice to be able to do it in the function implementation only:
Public Delegate Function Deserializer(Of T)(ByRef Buffer() As Byte, ByRef BufferPosition As Integer) As T
'Implementation of a func that matches the delegate'
Class A
Public Function Deserialize(Byref Buffer() as Byte, optional Byref BufferPosition as integer = 0)
....
At least this second way, the functions for the delegate will always have a value mapped to each parameter, although some may come from the function side and not the calling side.
I tried DbNull.Value but no luck. How do I assign a default value as null to a string parameter that is null in VB.NET? Its litte strange to see that VB does not have anything like plain null as most of the other languages do. Also what is the difference between null and DbNull and Nothing.
View 3 RepliesWhat is the standard way to implement optional query parameters in a .NET WinForms application?In other words, only query on a field if the value of a corresponding control is not null.
EDIT: I use a FillBy method which calls a query in my Access database. In the TableAdapter query editor, I just used WHERE (field1 = ?) AND (field2 = ?) ... I just can't find the "hook" to bind form controls to the table adapter query parameters and so that if a form uses the default value to not query on it.
Public Function Foo(ByRef a As AClass, _
Optional ByRef b As BClass = Nothing, _
Optional ByRef c As CClass = Nothing) As XClass
Error : Optional parameters must specify a default value.
I would just like to know why. optional parameters cannot have structure types?
View 4 RepliesI am interacting with VB code on a different tier, using a client-side c# program. The VB function signature looks like this:
Public Sub toggleExclusion( _
ByVal mouse As Double, _
ByVal study As Integer, _
[Code]....
I get an error saying no overloaded method of toggleExclusion takes 2 arguments?
I have an object, called 'PERSON' This person object has a title, firstName & Surname property as well as many other which are at the moment irrelevant. It also has a read only property called Fullname which concatenates the two or three parameters mentioned above depending on an optional parameter 'withTitles' passed over when you call PERSON.FULLNAME
PERSON.FULLNAME(true) <- Will add titles if there are any
PERSON.FULLNAME(false) <- Will give the name without the title
Public ReadOnly Property FullName(Optional ByVal withTitle As Boolean = False) As String
[Code]...
I get an error: PERSON does not contain a property of 'FullName'. If I change this to any other property that does not take a parameter it works as expected. Now I'm guessing that the binding procedure can't handle optional or mandatory parameters for object properties, is this right? Is there a better way to do it? I thought about looping through the collection to add them manually but that kinda defeats the object of DataBinding!
Is there an equivalent in Java to VB.NET's optional parameters?Also is it possible to switch on anything other than integers in Java?
View 1 RepliesIs it possible to make Color variable parameters in custom classes Optional?Everytime I try, it gives me a "Constant expression required" error.[code]
View 2 RepliesI have a custom Attribute class where the constructor takes one fixed parameter and two optional parameters. It is my understanding that one can supply one or more optional parameters by using 'named parameters' such as this:
Private Sub CallMethod()
Me.OptionalMethod(-1, z:=1)
End Sub
[code]....
Well, I thought, perhaps Attributes don't support named parameters. I know they can behave a little weird (they don't support all types in their arguments for example I think), so I thought little of it.But then... I noticed something else. If you take a look at my code of the attribute class again. Notice that I am using an attribute on that class as well... And what do you know: named parameters. Working just fine... The AttributeUsage attribute has the exact same configuration: one fixed parameter and two optional parameters. I seem to be able to call them using named parameters just fine, where I cannot call my own attribute constructor with named parameters...
Most of our code base is in VB.NET. I'm developing a project in C# that uses a lot of the assemblies from the VB.NET code.There are three relevant classes in VB.NET:
[Code]...
I'm using a stored procedure to updateinsert data into a table using MERGE. One of the items being inserted is a VarBinary file. Now if I wish to add a new file it's just a case of using ReadAllBytes as below, to remove the file I pass DBNull. Now what if other fields are being updated but the file is not being changed? I want the field to remain untouched unless I'm replacing the file or deleting it as above. I cannot add the file via the parameter again as it may only exist in the database, unless I read it first and write it back which seems pointless. [Code]
View 1 RepliesI have a search function de build.We are using pure ASP.NET w VB.NET We have multiple DropDownLists and we're building a search query with whatever was selected in those DDLs. My question is, how can I handle the blank values (unselected dropdownlist values) with the SQL Query ? I'm using AND operators in the query so if anything is blank it'll fail the search. If the dropdownlist has no selected value, i don't want the value to be part of the search. It would be easy to code with just 2-3 parameters, but we're looking thru at least 10 items and doing a SWITCH CASE or multiple IFs would soon become mayhem.
View 1 RepliesI am trouble shooting poor performance for the query I have posted below. Here is my problem: If I run the exact query below in sql server management studio or using .NET sqlclient the query takes an average of 14 seconds to run.
However, if in .NET I take out this part of the query:
DECLARE @time_diff INT
DECLARE @start_date DATETIME
DECLARE @end_date DATETIME
SET @time_diff = 2
SET @start_date = '05/04/11 00:00:00 AM'
SET @end_date = '5/4/2011 11:59:59 PM'
And use parameters in code like this:
sqlParameter = sqlCmd.Parameters.Add(New SqlParameter("@start_date", System.Data.SqlDbType.DateTime))
sqlParameter.Value = parameters.StartDate
sqlParameter = sqlCmd.Parameters.Add(New SqlParameter("@end_date", System.Data.SqlDbType.DateTime))
sqlParameter.Value = parameters.EndDate
Then the query takes about 2 - 3 minutes to run. Also, I have noticed that it takes about 2 - 3 minutes to run, if i replace the parameter values with string date constants and run in .NET or SSMS
--AND v.call_start_time BETWEEN @start_date AND @end_date
AND v.call_start_time BETWEEN '05/04/11' AND '5/4/2011 11:59:59 PM'
I found this article [URL] on cardinality and the query optimizer and I think it has to do with my issue but it doesn't seem to make sense in my case. According to the article, casts should be executed when determining cardinality. In my case this doesn't appear to be happening. The article also says to use parameters in place of local variables - which isn't working well with .NET parameters either. Regarding using a stored procedure instead: I have a variable number of parameters, I don't know how well it would work out. Even if this is the only option, then i would still like to know exactly what the problem is.
The query:
DBCC DROPCLEANBUFFERS
DBCC FREEPROCCACHE
SET STATISTICS IO ON
DECLARE @time_diff INT
DECLARE @start_date DATETIME
DECLARE @end_date DATETIME
SET @time_diff = 2
[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 traditionally coded empty strings like this "", but for a couple of years now, I have been using String.Empty.I also normally never use optional parameters, but I'm refactoring a solution that's tied into my ERP, and I don't want to break anything. One of the changes was to add a parameter to proc, which pushes a new parameter into the method from which it is called. I coded it like this:
Optional BackReferenceID As String = String.Empty
But I got a syntax error "Constant expression is required." I guess String.Empty is non-deterministic??? Anyway, it seems like a bug. The workaround is of course to use double quotes.
I just got upgraded from VB6.0 to VB2010. I'm trying to move some of my program functions over and I'm getting an error on the ones where I use optional... Public Function GetFolder(ByRef FTT As String, Optional InitFile As String)
I get the error at the end of the line, after the close par...the error is "optional parameters must specify a default value".
I was just practicing some coding and noticed that I was able to use class instead of Module in VB .NET. So I replaced my module to class and I got this error message:No accessible 'Main' method with an appropriate signature was found in 'practicevb'.practicevb
I made sure that the startup object was set correctly in Properties > Application > Startup Objects.The error message disappears if I change it back to Module but I would like to keep it class since the other parts of my code I changed to class and didn't return and error messages.
Class Atic
Sub Main()
Console.WriteLine("Hello, this proram will calcaulate the quadratic forumla ax^2 + bx + c")
Dim Quads As New Quads
[code]....
I am trying to print (to a text file) the fragmentation information give by Win32_Volume class using the DefragAnalysis method and have come up with the following VB.NET code:
Dim objReader As StreamWriter
objReader = New StreamWriter(FolderBrowserDialog.SelectedPath + "FragInfo" + "_" + CreationDate + ".txt")
Dim colItemsFragInfo As New ManagementObjectSearcher("rootCIMV2", "Select * from Win32_Volume where DriveType = 3")
[code]....
You do not need to defragment this volume.However executing this in Visual Studio returns the below:
Volume size: MB
Cluster size: MB
You do not need to defragment this volume.The point here is though it does NOT work under Windows Server 2008 R2, but does work under Windows Server 2003 (when executed in Visual Studio), WMI Code will work regardless of platform.
NB: i have played with the "Console.WriteLine" and changed it to "Debug.WriteLine" to output value to immediate window.
I am trying to call a method which has two parameters using thread. How can I do this? If I pass parameter to my thread.start() method, it is giving error.
View 1 RepliesIs there a Visual Basic.NET method that can convert method parameters into an array?[code]...
View 2 RepliesI am writing a alternative to GDI, and rigth now i am working at a logging function. The idea is that while you use the class to draw, it will write a logg of what you have done, which can be used to draw it back later. In that way i would be able to store a drawing with weary little disk usage.
[Code]...
How would I go about passing parameters to a method? I would want to do the following:
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
ReceivingUdpClient = New System.Net.Sockets.UdpClient(6767)
Dim receiveBytes As [Byte]() = ReceivingUdpClient.Receive(RemoteIpEndPoint)
Dim ThreadReceive As New System.Threading.Thread(AddressOf receiveMessages(receiveBytes))
ThreadReceive.Start()
End Sub
Private Sub receiveMessages(ByVal receiveBytes As Byte())
'INSERT CODE
<br/>
End Sub
How to pass a object that is initialized from a derived class to a method that has Interface as the parameter?[code]...
View 1 RepliesI'm trying to use the Shell method however I'm having trouble because I want to open the file a specific way.
For example,
Shell("C:x.exe" -window)
However this gives an error.
just want to know what is the difference between these date values?Once some one told me that its difference is server date and client date but not sure which one he meant.Below is 3 type of date currently I'm using and don't know what is the difference between them.
DateTime.Now is from System.DateTime.Now
Now is from Microsoft.VisualBasic.DateAndTime
Today.date is also from System.DateTime
