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 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 am trying to have an optional Date value in one of my sub but since you cant set Date to nothing, this doesn't work. And i cant set it to the Date.minvalue inline.
Private Sub abc (ByVal A As String, Optional ByVal B As Date = Nothing)
End Sub
So, i went and set it to some date in the past.
Private Sub abc (ByVal A As String, Optional ByVal B As Date = #1/1/2001#)
End Sub
what would be the proper way to handle the default value for an optional Date?
However, 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.
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 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?
View 4 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 have a problem during defining a Sub routine in VB.Net. I am defining a sub routine which is as under
Private Sub ActivateControls(rdbutton as RadioButton, Optional txt as Textbox, Optional txt2 as Textbox)
End sub
When I call this sub routine It gives me the Error that Each Optional Parameter must specify a default value. So, Here I can't understand that what can be the default value of a textbox. What default value I can use here to remove this error.
I think this is a pretty basic question, but I just want to clarify. If I have a variable with a null value, and pass it as a parameter that is optional, will the parameter get the null value, or the default value?
dim str As String = "foo"
dim obj As Object
//call 1
[code].....
How can you set a function optional argument to null? For example, I want to set the optional argument intCode equal to Null. These arguments are used to send to a stored procedure as parameters.
Public Function pubfnc_SetCommentCode(ByVal strFieldName As String, ByVal lngResultID As Int32, Optional ByVal intCode As Int32 = DBNull.Value) As String
My problem is this (apologies if this is a little long ... hang in there):I can define a function in VB.NET with optional parameters that wraps a SQL procedure:
Sub Test(OptionalByVal Arg1 As Integer _
Optional ByVal Arg2 As Integer _
Optional ByVal Arg3 As Integer
[code].....
I am getting error [07002] the # binded parameters < the # of parameters makers, i checked both parameters were perfect even though i am getting this error here is my code
[Code]...
Just kind of curious about something: why does VS (vb and C#) default params to pass-by-value?I almost never need or want to pass anything by value. Maybe this is some reflection on the way I code. I would never manipulate a value type param directly; i would just return the new value from a private variable... and I just don't see the need to do the background work all the time to add copies of everything to the stack. Why wouldn't I just about always want to pass-by-ref?
View 5 Replies[code]Is j passed as value ByVal or by reference ByRef?Or does it depends of the data type? What if I have a complex object passed as the value?
View 2 RepliesI am getting this error when debugging a VB application. The method that is being called when I get this does not have any arguments. Definitions in code are as follows with names changed to protect the guilty
[Code]...
The question is, if the method is not defined to accept argments, then why am I having a debug assertion while debugging that says that the arguments are not optional?
I have an Image.OCX which is build on 2008. This is used by VB Application.Many OCX methods are not used in Application. I want to delete unused method from OCX.Step for method deletion.
Delete exists Method from .ODL File i.e //[id(181), helpcontext(11)] long CreateImage(ID id);.
Delete
CreateImage same function . Delete //DISP_FUNCTION(CImageCtrl, "CreateImage", CreateImage, VT_I4) from Ctrl.cpp.
Delete interface ID from AFX_DISP_ID.
[code]....
Following Error Message display "Run Tim error '449':Argument not optional."
let me know is that possible to delete exist method from OCX and How?
I want to start osmon.exe with diffrent parameters, eg. Default, Osmon2, Osmon3, Osmon4 and Osmon5.After Default has started it must wait 10 seconds, after osmon5 has started it must wait 15 seonds.Then is must write the PID# to txt file.I have the code, but when I run it, it only shows the console for 1 second, and then nothing is happening after that.
Imports System.Diagnostics
Imports System.Timers
Imports System.IO
[code]......
I am trying to upload a file to Mainframe machine from my VB.net application. I am getting the following error.The remote server returned an error: (501) Syntax error in parameters or arguments
[code]...
I want to pass an optional parameter to a function of type System.Drawing.Color. The problem I am having is that when I declare the function it says "Constant expression is required" but I have tried variations of the following, including integers, full qualified indentifiers, even old vbWhite constants to no avail.
[Code]...
<asp:AccessDataSource ID="productsubtype" Runat="server" DataFile="~/access_db/db_tables.mdb"
SelectCommand="SELECT [type], [id],[subtype] FROM [prod_subtype]"
UpdateCommand="UPDATE [prod_subtype] SET [subtype]=@subtype WHERE [id]=@id"
[code]....
When i press delete button in gridview i am getting error
I'm creating a login form with two text boxes and two buttons. I'm getting an error in the button1 click routine which is supposed to validate the userid and password. The error is in the Dim Reader line. It states; No value given for one or more required parameters.
Imports System.Data.OleDb
Public Class Form1
Dim MaxRows As Integer
Dim inc As Integer
[code]....