This is a question I have asked myself many times in the past as I nested using statements 5 deep. Reading the docs and finding no mention either way regarding other disposables instantiated within the block I decided it was a good Q for SO archives.
[Code]...
I am implementing IDisposable for a class and while disposing there is a internal list of disposable objects. Should I be disposing those object by looping through them.
public Class MyDisposable
Implements IDisposable
private _disposbaleObjects as new List(of OtherDisposables)
[Code].....
I have two lists declared as follows:
Dim lstDBItems As New List(Of DBItem)
Dim lstAppItems As New List(Of AppItem)
I am trying to do something like this:
I've a function which returns List(Of AppItem):
Function GetAppItems() As List(Of AppItem)
'...
End Function
In the above function I populate lstDBItems and then write the return statement like follows:
Return lstDBItems.Select(Function(x)
dim oItem As New AppItem()
oItem.Property1 = x.DbProperty1
[Code]....
The weird thing is the code compiles, but on rumtime I get a type case error.
Please excuse my choice of wording and/or mixup of terms, I am a dummy when it comes to socket programming. I am trying to connect to a TCP server, write a message and process a response. I use the following code:
Dim tcpClient As Sockets.TcpClient = New TcpClient()
tcpClient.Connect(hostname, 9080)
Dim networkStream As NetworkStream = tcpClient.GetStream()
[code].....
I recently wrote a section of code wherein upon finishing, I received a warning from the compiler telling me that one of my variables is being used before it is assigned a value. In practice, the method call on this object will never be made without the object being instantiated beforehand. Here is the snippet of code
Try
fs = New FileStream(fileName, FileMode.Open)
Dim PolarMatrix As PolarMatrix
PolarMatrix = DirectCast(bf.Deserialize(fs), PolarMatrix)
[code]....
I assume I'm receiving this warning because the first line in the Try section may be the line to throw the error, and the Object will never be instantiated. FileName though, is a variable being passed to this method which has already been checked for errors, so it is guaranteed to be correct. The error I'm expecting to perhaps be thrown comes during the deserialization.
So my question: When warnings are given on objects that the compiler thinks may not have been instantiated, does this overrule the user knowing that a problem will never arise on that line? Is it sometimes necessary to add code simply to appease the compiler?
If I have a class that inherits another class in which there are objects that are disposed in the dispose() procedure, do I use mybase.dispose? ex Class A inherits Class B. [code]
View 2 RepliesI have been searching for memory leaks in my application and come down to this weirdness. I have a class which implements IDisposable and one single event in it as shown below:[code]
View 1 RepliesI create an Instance of Access to view a report through my app.I would like to check if an Instance of Access has either already been opened by the user, or by the app. If so, use that instance.
Dim oAccess As Access.Application
Public Sub CreateAccessInstance()
Try[code]...
As it stands now, It creates multple MSACCESS.EXE processes which are running until I exit the app.
I think I just need a push in the right direction. I cannot seem to get my sub from an instance of my class, once instantiated, to run when I click on the button. My Code in the class is
When I click this:Private Sub btnBark_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnBark.Click
mydawg.bark()
End Sub
[Code]...
When developing a Windows Forms Application, I can see in the Application.Designer.vb file where Me.MainForm = Form1, but I can't find where/how Form1 actually gets newed-up.
View 3 RepliesI am new to WPF and custom controls.I have implemented a custom control in VB with WPF and MVVM based on Davids example: [URL]..I have a custom control libary and a reference to my project to implement my control.I implement my contol in the View via XAML:
[Code]...
Is it possible to change the upperbound of an array once it has been instantiated? I want to change the upperbound in an array so it matches the number of items that hold a value.
View 11 Repliesproblem with no event fired after the wrapped ocx object with aximp sent out the message in a console application testing.
View 3 RepliesVB.NET: What is the best way to ensure that a particular object may be instantiated only once during program execution?
View 3 RepliesI have a customer intranet (ASP.NET / VB) thats instantiating an asp.net session checking various things in the dblogin process. The Intranet has various sub-systems.The marketing sub-system requires an app_role to be assigned to the Intranet user for them to view the section.I need to create a new booking form for this section but the code appears to use a generic form which is use throughout the site in various other sections. So its not a good idea to ammend what is currently there.Create a new application in C# / ASP.NET and also in IIS. (rather than a new site, create an app within the Intranet site in IIS)Will I be able to check for the session thats currenting set in the cookie?If the session is open then the user is able to see the Intranet and I assume I will need to do some checks for the app_role too.I am simply going to put the URL for the app in the menu for marketing and then do another check just incase someone gives the URL to someone who doesnt have access to the menu.Will i be able to check and use the cookie thats been instantiated by another application?
View 1 RepliesCan you raise events from a class that has only shared members and doesn't get instantiated? I originally had the class members non-shared and created instances of the class where I need them. I had the events being raised and everything worked as expected. But as the class members are actually application level and do not need instancing, I converted all members in the class to shared so they could be accessed from anywhere in the program without creating an instance of the class. But WithEvents requires the creation of a class instance. I've done that and it seems to work fine when using an instance. And since I need the events handled in only one class, I can create the instance in that class and let all other areas access the class directly, without creating an instance.
View 10 RepliesI have a .Net 4 WinForms app that generates a DLL, calls CreateObject on the generated DLL then calls one of several methods that the DLL contains. The DLL is eventually used by a separate app. This WinForms app is just to generate and test the DLL hence why it can generate the DLL multiple times.The problem lies in the fact that calling CreateObject on the DLL locks the file to the process. The next time the DLL is generated it can't overwrite the previous DLL file on disk without closing the app completely and starting it again.
I've tried Marshal.ReleaseComObject, executing the CreateObject in a separate AppDomain, even setting the variable holding the COM object to a different COM object via CreateObject, manually calling GC.Collect() and a whole host of other things but none result in unlocking the file.The code flow is basically (simplified and generic names, etc.):
...
' Compile and generate DLL that is COM enabled and works fine
...
Dim foo As Object = CreateObject("Bar.Foo")
[code]....
is there a way to release a file lock on a COM DLL that has been instantiated via CreateObject without killing the process?
Note: this is a continuation of this original issue. I now have the DLL registering without locking the file but now the issue is with the CreateObject call not the DLL registration.
This runs correctly, but Excel remains active after close.
If I don't create the range objects below, everything seems to work (with no output of course). Does anyone have any idea on how to keep Excel from staying in memory. Also... in the tests I'm running, I do not make the application visible.[code]...
I have created a simple custom control - we will call it a "panel with buttons". Here is how I instantiate it:
[Code]....
So what I wind up with are multiple instances of my panel. Each of these panels has a button on it called Button1.
My question is - how do I capture this button event in a way that I will know which panel index it came from?
In the custom control there is only the Button1_click event - and when I click on it in any of the multiple panels I manually instantiated the event does occur, but how I can tell which one of my instantiated buttons were clicked...
I am working on an application that requires buttons and links to be added during run time, it's a bit like a flow chart. The buttons are used to display information similar to a multi line text box, but I also use the click, double click and mouse events for these buttons. The links are drawn as label controls. My problem is that I want to control the format order of these controls with the buttons always being on the top layer and the labels one layer back so that when labels are added they aways pass behind the buttons. If this was done at design time it is very easy to use the menu Format > Order to get overlapping controls displayed the way I want. But, the controls placed on the form at run time do not have a Format or Order property.
View 1 RepliesUsing VB 2005 with .Net 2.0.
I have a form which loads another form, does a little initialization, then hides itself and shows the other form. When the user finishes with the second form, it returns back to the first.[code]..
I thought it might be a timing/speed thing (somehow the server was too fast to load or unload the form), but I put a 5 second sleep between every line of code and that didn't help at all.
i am facing a huge problem with the "Cannot access a disposed object. Object name: 'TreeView'." error.
On a windows forms of mine i use a custom windows explorer object.
And here come the code parts...
On the selected node event, i load the images found within the selected directory to the FlowLayoutPanel.
Private Sub ExpTree1_ExpTreeNodeSelected(ByVal SelPath As String, ByVal Item As ExplorerControls.CShItem) Handles ExpTree1.ExpTreeNodeSelected
'Loop until all images are loaded.
LoadImagesToFlowPreviewPanel()
[Code]....
I found an error - cannot access a disposed object in my project.
i using vs2005.
but before this, i using vs2003 and this error doesn't occur.
but when i convert to vs2005 and debug, this error occured.
I have a windows form in .NET that will serve as a wizard to achieve something. This contains 3 steps: Step1, Step2, Step3.
Each step is again actually a user control. Main form contains a panel that display the current Step. When I change among steps then:
1) Dispose the current user control by calling its Dispose() method.
2) Clears the main form panel
3) Initialize the user control of next step and add it into the main panel
Now, the issue is, User control of step one contains one more user control. When I change to another step and come back to step 1, I get following error:
"Cannot access disposed object."
Because I have to first dispose the user control before actually displaying the another step. And when I come back to step 1 and tries to open the user control on step 1, it gives the aforementioned error.
Protected Overrides Sub LoadForm()
MyBase.LoadForm()
Try
'StartProcess might be causing an error (error msg is issue with loading config, which would be incorrect)
StartProcess()
[Code] .....
I can run this 100 times under the exact same conditions and it seems like 40 times it will crash with the following error:
"Cannot access a disposed object. Object name: 'frmImportExport'."
It will either die on
'within StartProcess()
Dim __Delegate As New _Delegate(AddressOf StartProcess)
Me.Invoke(__Delegate)
or
Dim D As New _Delegate(AddressOf SOPERATION)
The form isn't being disposed manually anywhere that I see, and this code is being executed on formload. It's a subform that is to be displayed within a main form.
How do I re-open a form that has been disposed?I tried using GC.Collect() which did not work.I have 2 forms.The first form being the main form and the second being the secondary form. I open the secondary form with form one.Form 2 two opens and after I am done with it I close it.Now I want to open up the second form again and BAME! Error.Cannot access a disposed object.
View 4 Repliesi have a query. i created two forms a and b. if i click ok button in form a , form b should open. and i did it. but again if i click the button it says that i can open a form once it is disposed.
View 1 Replies"Sometimes your code requires an unmanaged resource, such as a file handle, a COM wrapper, or a SQL connection. A Using block guarantees the disposal of one or more such resources when your code is finished with them. This makes them available for other code to use. Managed resources are disposed of by the .NET Framework garbage collector (GC) without any extra coding on your part. You do not need a Using block for managed resources."
So, which unmanaged resources must disposed manually and which disposed automatically of by the .NET Framework?
I tried running code analysis the first time and found what it appears many others on SO doing the same have found: an abundance of
In method 'SomeMethod()', object
'SomeObject' is not disposed along all
exception paths. Call
[code].....
[code]in this code, do the objects con and cmd get disposed because the return statement is placed before the end using statement.
View 1 Replies