Why if you pass an object as byVal into a method is it then treated as if it were byRef? I know you're only passing the reference across when you pass an object variable but why doesn't VB force you to decalre the header as byRef?
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If you pass the property of an object to a function ByRef, and the function doesn't modify the ByRef parameter, the property Set is still called.
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Below I tried to do an Example:
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Below is the called method: Friend Sub SplitOU2(ByVal inDN As String, ByRef OUDN As Object, ByRef Organisation As Object, ByRef VerksamhetTyp As Object) By doing this I can skip to declare the in this example "useless" variable Dim VerksamhetTyp as Object = "".
I work with C# 99% of the time. However, I'm having to update some legacy VB.Net code and encountering an issue with VB.Net code syntax. The error that I get is "ByRef" is underlined and "Expected Expression" tag shows up when you hover over "ByRef". The "FooDetail.Load" function is written in C# and expects a List object passed as reference. Don't have any trouble using the same function in other C# classes. Can someone indicate what is wrong with below VB.Net code.
Dim FooDetail As New clsFooDetail()
FooDetail.FooID = FooID
Dim lstFooDetail As New List(Of clsFooDetail)
FooDetail.Load(ConnectionString, "Stored Procedure", ByRef lstFooDetail as System.Collection.List(Of(clsFooDetail))
This is the code:
Public Class userDefClass
private b as integer = 1
End class
Public Class Form1
private SomeClass as new userDefClass
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) [Code]...
I am making use of a 3rd party dll and am encountering some strange behavior in VB, which doesn't occur in C# Perhaps someone can explain what is going on. Anyhow, I am making use of a method in this 3rd party library which accepts an array parameter ByRef. The end result is the variable should remain null after the method call, but it is returning initialized for some reason.
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Is it considered bad practice (VB.NET or any language) to code a function with both ByVal and ByRef parameters as used in my getFile function below?
Function getFile(ByVal channel As Integer, _
ByRef Filename As String, _
ByRef Filesize As String) As Integer
End Function
Dim status As Integer
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Just wondering if it's possible to store a reference to an object in a variable.
I will elaborate:
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I would like a label to always show the current value of a boolean. This will change a lot of times and would like the label to ALWAYS reflect this.
Is there some kind of way to have the label set to the boolean byref (so its always the same). Currently I'm assigning the label.text = boolean onLoad, so if the boolean changes after that its not reflected.
How would I create a variable and assign it to another variable and when I change one variable it will be changing the other also?
View 3 RepliesI pass this class i created a variable by reference and i want that reference to be assigned to m_Text so that when i change m_Text it changes the TextValue variable i passed. Example:
Dim test2 as String = "ok"
Dim test as New GeneTextBox(test2)
'then some one changes the text in the GeneTextBox and i want it to change the test2 string...
Public Class GeneTextBox
Inherits Windows.Forms.TextBox
Private m_Text As String
Public Sub New(ByRef TextValue As String)
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I have a subroutine that passes several variables to the called subroutine.I want one of the variables to be updated by the called subroutine and then check for the change in the calling subroutine. My code works fine except that the variable I am checking
calling Sub routine
Code:
Public Sub ProjectName_Exit(Cancel As Integer)
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How can I get the name of the object that was passed byref into a method?
Example:
Dim myobject as object
sub mymethod(byref o as object)
debug.print(o.[RealName!!!!])
end sub
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I'm using this for logging. I use one method multiple times and it would be nice to log the name of the variable that I passed to it. Since I'm passing it byref, I should be able to get this name, right?This would give you the parameter name in the method and it's type, but not the name of the variable that was passed byref.
using system.reflection
Dim mb As MethodBase = MethodInfo.GetCurrentMethod()
For Each pi As ParameterInfo In mb.GetParameters()
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If you put that in "mymethod" above you'd get "o" and "Object".
is there any collection in vb.net which store object as byref and not byval.
View 4 RepliesI have a connection string issue, sometimes when I change servers, I run into an issue of where My.Settings.Save doesnt save the changes sometimes. I created a text file when I change my connection string to see if it is saving the right information and it is, but sometimes my settings does not reflect the changes after calling my.settings.save.
View 1 RepliesUsing Visual Basic 2008 Express. I need to pass a variable to another form. Or else make the variable visible to both forms.
View 4 RepliesI was shocked just a moment ago to discover that the following is legal (the C# equivalent is definitely not):
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I'm using a TabControl and have overridden the DrawItem event to produce my own background and foreground colors for the header text. It looks good but there's still grey color around each header. I thought maybe the Padding property could be set to (0,0) but that seemed to have no effect.
View 2 RepliesToday I discovered that something I had assumed about VB.NET for many years was not true (worrying!). I assumed that a variable declared within a loop had a lifetime of the iteration it was declared in, but in fact it seems it has a lifetime of the whole procedure.[code]I had assumed an output of False, True, False, True but instead it is actually False, True, True, True..In C# the equivalent code would not compile as you would get a compile time error of Error "Use of unassigned local variable 'var1'".I realise there are many ways to fix this and that best practice would be to declare the variable outside of the loop and reset it at the beginning of every loop through.I find this behaviour so counter-intuitive to me that I would like at least a compile time warning in VB.NET when/if I do this. (I could also then set this on any projects I already have and get warning that would allow me to check that my assumptions aren't causing errors).Does anyone know how/if I can get this to generate a compile time warning in VB.NET? Am I the only one that finds this counter-intuitive?
View 1 RepliesI am working on a application that has quite a few functions involved and have been thinking of the following: If I have a function that has a few paramaters, is it more efficient to pass the objects to the function(Example 1) or reference the objects in the parent(Example 2)? Does it matter if the objects are large or not?
Example:
Class mainform
Public myGenericList As New List(Of String)
Public myDatarowArray() As DataRow
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I am currently working with a gridviews in asp.net(vb). I have it where I am able to pass information from gridview1 to gridview2 on the next page. However, what I need to do now is pass a variable from a column in gridview2 to the header of that page. i.e. in Gridview2 we have a column and all results are the same, the column header is StoreName and all the data for column is Sears. I know how to make the entire column invisible, but at the top of the page I need a sentence that looks like this:
Store Information for Sears
I am having trouble with what the code would look like for that line, all the thing I have tried have resulting in using a variable before it is declared. I need this line to be dynamic as the results will not always be for Sears.
I have the following VB code.Dim cmd As New MySqlCommand("SELECT code FROM decoder WHERE ann_id = @aid", conn) cmd.Parameters.AddWithValue("@aid", 1)Dim reader As MySqlDataReader = cmd.ExecuteReader()
The reader.Read() then gives me nothing, however, if I replace the code by.Dim cmd As New MySqlCommand("SELECT code FROM decoder WHERE ann_id = 1", conn) Dim reader As MySqlDataReader = cmd.ExecuteReader() reader.Read() gives the correct result. Tried using Add instead, doesn't help. What am I missing here?
Note: this is not a duplicate of Jeff's question. That question asked "Is an equivalent?" I know there isn't, and I want to know why! The reason I ask is that I've only just become clear on how important it is, and the conclusion seems very strange to me. The Exception Handling block of Microsoft's Enterprise Library advises us to use this pattern:
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The policy is defined in an XML file, so that means that if a customer has an issue, we can modify the policy to assist with tracking down (or perhaps papering over) the problem to give them a fast resolution until we deal with it properly - which may involve arguing with 3rd parties, about whose fault it all is. This is basically an acknowledgement of the simple fact that in real applications the number of exception types and their "recoverability" status is practically impossible to manage without a facility like this.
Meanwhile, the CLR team at MS says this is not an option, and it turns out those guys know what they're talking about! The problem is that right before the catch block runs, any finally blocks nested inside the try block will be executed. So those finally blocks may do any of the following: Harmlessly modify the program state (phew, lucky). Trash something important in the customer's data, because the program state is screwed up to an unknown degree. Disguise or destroy important evidence that we need to diagnose an issue - especially if we're talking about calls into native code. Throw another exception, adding to the general confusion and misery.
Note that the using statement and C++/CLI destructors are built on try/finally, so they're affected too. So clearly the catch/throw pattern for filtering exceptions is no good. What is actually needed is a way to filter exceptions, via a policy, without actually catching them and so triggering the execution of finally blocks, unless we find a policy that tells us the exception is safe to recover from. The CLR team blogged about this recently:
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I am using the VB ReportViewer and report designer. I am not using the report wizard as I have had no success creating the report I want that way (I'm new to all this).
I have created a view holding all the columns I want to report on. Half the columns have values to be displayed in the body of the report in tabular form. The other half contain values on which I wish to group. Although there are several columns in this set, the values do not change except when the group value changes. Eg
Group col1
Group col2
Group col3
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I cannot discover how to achieve this using the tools provided with the report designer.
I have some classes, BsfciFile and StudyFlashCard. Bsfci is the extension to which I save my set of flashcards in an INI format. I am currently working to transform my code from using Windows API calls to access the INI to using a IniFile class that I found on the internet. I would like the BsfciFile to have a Array of StudyFlashCard objects, but I would like the StudyFlashCard class to use the IniFile class object contained in the BsfciFile class. I can pass the IniFile from the BsfciFile class to the constructor for the StudyFlashCard class, but I want it to modify the same IniFile as the BsfciFile class has later on.
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Hi
I've got a pretty general question about the best practice in passing an object reference to a Form in VB.NET. My form is a dialog and I've created an overload ShowDialog method, where I pass an Object into it ByRef.
The trouble is, I want to be able to refer to that Object throughout my dialog Class and not just in the ShowDialog method. For instance, some of my Events for controls on the form, need to reference that object.
I know I could create a local Private variable in the Class and assign it to the passed value, and then use that value. However I'm thinking this isn't very efficient because it would (I believe) create a new copy of the Object (which is a complex, large class in itself).
i have this error in the line of with xl.active......Object variable or With block variable not set.
Dim xl As Object
xl = CreateObject("Excel.Application")
With xl.ActiveSheet.QueryTables.Add(Connection:= _
"TEXT;C:Documents and SettingsUserDesktop429MEDICA2.TXT", _ Destination:=xl.Range("$A$1"))
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Now I have the need to get a current value from a bindingsource in a property of a user control.In a previous thread I had tracked down the "Object variable or With block variable not set" to the return in the Get block of a property. At the time I was only using the Set so I just commented out the offending code until I needed it.
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The error does not occur during a system compile, only upon saving the container object of the user control. As I said the Set works correctly, only the Get causes the error.I would like to know what I am missing/misunderstanding and am open to other suggestions of handling retrieving the current value of a bindingsource in a user control.
i had a class called Tag with a structure like:
public class Tag
private _members
public properties
public shared database_methods
end class
this class was tailored for mysql database. i'm currently adding access 2007 support so i split tag into tag and tagdata with structures like:
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I'm having trouble tracking down what is wrong and causing the above error. This only occurs when saving the design view in VS 2012. The code builds and runs fine.Full error text:Code generation for property 'CompanyValue' failed. Error was: 'Property accessor 'CompanyValue' on object 'ContactViewUC1' threw the following exception: 'Object variable or With block variable not set."
CompanyValue definition in ContactViewUC:
Public Property CompanyValue
Get
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