VS 2008 Transfer A Custom Event Through The Generic Collection?
Dec 22, 2009
To the point: I need to transfer a custom object's event through a generic collection object containing these items so that any class using the collection can see that changes were made to one of the items in the collection.
I.E. An item event that triggers a collection event
[Code].....
Due to the application requirements, I need the Collection and Items to send immediate notice of various changes that occur to the Collection Class and its items. I've already got my events set-up regarding for the Collection Class, but I'm struggling with coming up with a workable solution for raising events for the items.
I've got an event for the DeviceLayer item set-up, but how do you transfer that event through the CollectionClass so that any other class using it will see that there was a change to one of the items in the collection?
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Feb 25, 2009
I wrote a class which imports System.Collections.ObjectModel. For the management of the collection, I've written:
Default Public ReadOnly Property Item(ByVal vntIndexKey As Integer) As ItemType
Get
Return CType(mCol.Item(vntIndexKey), ItemType)
[code].....
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Jun 19, 2009
I have several custom classes in a VB.NET (VS2008) project which are related to each other through generic list collections. The lower tier classes refer directly to some of the parent classes (to make it easier to refer backwards up the chain). My question is, is it possible to add the reference to the parent class when the item is added to a collection, when that collection is a property?
Below is some sampling of code to illustrate.
Public Class FlexServer
Private m_FlexLicenses As List(Of FlexLicense)
Private m_Modules As List(Of FlexModule)
Public Property FlexLicenses() As List(Of FlexLicense)
[code] .....
In the code above I have the FlexServer class which refers has two lists as properties, one for FlexLicense and one for Modules. The FlexLicense class has a property to refer back to the FlexServer class that "owns" it. In order to update this property in code, I have to add the FlexLicense to the FlexServer.FlexLicenses list AND set the FlexLicense.FlexServer property. What I am looking for is, is there a way (in the property definition or wherever) to both add the item to the list and alter it at the same time?
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Dec 13, 2011
Cookies to be stored in folder and on close delete the cookies The ability to watch youtube vids, view images, and play js/flash games good security, no ads?
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Jul 8, 2009
Is it possible to have a sub that is triggered when any control of a specified type is clicked (or some other interaction), and then within the code of that sub, determine the sender and depending on the sender perform an action?For example, you create buttons dynamically, and assign them a name based on a counter that tells the number of buttons on the form. Now you click on a button, but there was no code written for 'button123.mouseclick' specifically. Instead, you get the name of the sender (button123) and you do something specific to that button.[code]
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Feb 8, 2010
I have been researching for a couple of days now and to no avail. Does Anyone know how to make a custom collection that take advantage of the collection editor? I would like to be able to have 3 Color Values, 1 Boolean and 1 String.
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Jan 23, 2010
I have the below code and it works fine, it's this way because I need to manually calculate some data before adding it to the Listview control.
Code:
Dim mList As List(Of ListViewItem) = mDataBase.GetRecords(LvwChecks, "CheckGroups", <Query>, GetType(CheckItem))
If mList.Count > 0 Then
[Code].....
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Sep 14, 2011
I know its generally a big No-No to modify a collection that you are iterating through but unfortunately i didn't design the code that i'm trying to modify. All over the place the following is done:
for each log in Logs
logs.Delete(log.LogId)
Next
Delete pretty much just deletes the log from the database and removes it from the collection. Previously the Logs object was using a Non-Generic collection. I changed it to use a Collection(Of Log) so i can LINQify the object. Now every time i call next/.MoveNext is called after the first delete the following error happens:
InvalidOperationException:"Collection was modified; enumeration operation may not execute."
I understand why i'm getting the error but i don't understand why it never happened with the Non-Generic version. Is there anyway to get around this error? There really is no way i can take the time to change every place where the delete logs like this (codebase is large). Id like to just remove the code in the Delete function where it removes it from the current collection because i'm assuming no code does anything with the collection after its done but you know what happens when you assume.
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Jan 16, 2010
I'm trying to create an inherited version of the ListView control that (among other things) should have a different background image if the listview is empty to if it has items.Obviously you can easily enough test the count of the collection, but I need to be able to react to the event, however there doesn't appear to be any event related to adding/removing items.
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Jul 11, 2011
I have an ASPX Custom Control which is supposed to load it's properties into an internal collection (defined with PersistenceMode.InnerProperty). Here's the ASPX
<cc:CustomControl runat="server">
<Queries>
<cc:QueryTypeOne ... />
[code]...
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Apr 8, 2009
I have a class which extends HashSet(Of T).I am trying to evaluate some custom properties of this HashSet during execution and make decisions based on those values.
During debugging, I am pausing execution and adding a Watch on my instance of this HashSet.
The Watch only provides me with a view of the Count of the HashSet and the objects contained by the HashSet.How can I get the Watch to show me the other properties of the HashSet?
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Jul 11, 2009
Why won't XMLSerializer process my generic list?
Sub Main()
Serializing()
End Sub
[Code]....
I get an exception on the "Dim ser" line, saying "Testing.Module1 is inaccessible due to its protection level. Only public types can be processed." ("Testing is the name of the application, and "Module1" is the name of the module; this is a console application).
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Apr 16, 2011
Ok say I have this Dim MyQueueOfClients as new Queue (Of TcpClient) I also have two threads.
In thread one a TcpListener waits for connections then adds a connected TcpClient to MyQueueOfClients.
MyQueueOfClients.Enqueue (TcpClient)In thread two I then check to see if there are any Clients in MyQueueOfClients. If so I then remove them from the MyQueueOfClients.
MyTcpClient = MyQueueOfClients.Dequeue I think the question Im asking is this thread safe?
Can I Enqueue and Dequeue at the same time from different threads?
Well it helps if you read everything. I have just read this as well
A Queue(Of T) can support multiple readers concurrently, as long as the collection is not modified. Even so, enumerating through a collection is intrinsically not a thread-safe procedure. To guarantee thread safety during enumeration, you can lock the collection during the entire enumeration. To allow the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.
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Mar 1, 2011
Say a collection grow. Once it's size reach 10k, I want to get rid the first 9k. How to do so?Oh ya I could use removeRange.Is there another function that will output say, the last 1k of the element, say if I do not want to remove anything? Something like tail or something.
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Oct 22, 2009
This is really a continuation from my earlier post. I've never worked with this datatype/collection (system.collection.generic.Ienumerable) before so I'm struggling to declare the query globally so I can reference the results within other sub routines/functions. I also am struggling to convert it to other types.how I can convert the collection of xml elements/system.collection.generic.Ienumerable into an xmltextreader (I know I will have to change the query below as it select the value of the node and not the node itself) I imagine by converting the query result to system.IO.stream My first port of call was MSDN but I find the material very difficult to understand for this particular subject.
[Code]...
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Aug 18, 2011
There are a lot of different generic collections available, so the wisdom in creating a new one may be questionable right from the start.However, I often find myself wanting the same features from my custom generic lists, but cannot quite find all of those features in an existing object; namely, I would like to have a generic collection which works like a List or Dictionary (much like the System.Collections. ObjectModel. Keyed Collection(Of TKey, TValue)), but also works like a BindingSource does when it is bound to an ADO object (that is, it supports full sorting and filtering as well as currency).A feature I almost never need however, is transactional adds (the BindingSource's ability to 'cancel add-new').Again, with so many existing collections out there, I should take a moment to go over the reasons why none of them quite meet my needs.There is the System. ComponentModel. BindingList(Of T) which would provide some of the functionality of a BindingSource, but has strict requirements about the type {T} implementing IComparable in order to support sorting, and does not provide filtering (it is not an IBindingListView).It also only maintains a base item list by index, so does not provide keyed access.We could use simple databinding with a custom list inheriting from System.Collections. ObjectModel. Keyed Collection(Of TKey, TValue) bound to a BindingSource, but again TValue would have to implement IComparable to support sorting and we would still not have filter support.So to get all the features I was after, I decided that the best thing would be to create a new generic collection object which implemented IList, IDictionary, IBindingList, and IBindingListView (along with a few others) and would be capable of serving as a simple list, or as a binding source while providing full sorting and filtering over any newable object type.
To that end, I've created the KeyedObjectModel which contains the KeyedBindingList(Of TKey, T) generic collection/binding source. This collection can be used as a typical list, or as a binding source (you do not need an additional BindingSource component between the collection and UI controls, although you could certainly have one).Various constructors are provided in order to initialize an instance of the collection as either an enhanced list-dictionary, or as a complete BindingSource.Any object that has a public constructor which takes no arguments can be used at type {T}, providing that the object has a property of type {TKey} which will contain unique values for each entity in a given collection.If the object implements System.ComponentModel.NotifyPropertyChanged then the collection will also bubble up property changes on the current item to the collection's CurrentItemChanged event.An implementation of IComparable on type {T} is irrelevant because sorting and filtering are performed on the property values of {T} based on the type of the specified property.The current design of KeyedBindingList(Of TKey, T) is in an 'alpha' stage.The class is mostly complete from a feature implementation standpoint, however, the code has not yet been optimized and the base collections of values, keys, and view are being maintianed in generic lists of their own, rather than raw arrays.However, even without performance tuning, the collection appears to be performing quite well, up to a few thousand entries, given the amount of flexibility and funcitonality it provides.At this stage, I would really love to get some peers to try using the compiled DLL and beat up the collection a bit.Once the code has been proven and optimized, I will publish it as an example.It is a fairly complex class though (currently made up of eleven or so partial classes) so I don't really want to post the code until it has been optimized. [code]
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Apr 16, 2010
i have a BindingSource Bound to a DataTable which is bound to a DataGridview. I have Insert, Update, Delete commands etc. Private Sub InitialiseDataAdapter()
[Code]...
You cannot set the NewObject property when bound to a DataView or DataTable because you cannot add a new DataRowView to the list.
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Jul 1, 2010
What is that ... Well I was not too sure how to title this question, and even after telling the client it was difficult if not impossible, he insists it's what he wants.. so here goes the question.. The client has several SQL systems running on site that collect data from different processes (Between 1 and 10 minute intervals depending on the process been checked). Note: these systems sit on different parts of the site..
[Code]...
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May 10, 2010
I created two classes. One class is StudentClass and the other is HomeroomClass. The HomeroomClass contains a readonly property as a generic list of the StudentClass. [code]...
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Jan 1, 2011
Here are essential excerpts for the code creating the class and the page using it:
Imports System.Collections.ObjectModel
Public Class Test (Of T as xyz)
Inherits Collection (Of T)
[code].....
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Jun 17, 2009
I am trying to implement a simple IEqulityComparer to use with LINQ collections. I have written the following code which is reduced to its simplest form for discussion purposes...
Public Structure bob
Dim SiteID As Integer
Dim fred As String
End Structure
[code]....
The problem that I have is that both functions throw the compiler warning "function 'getHashCode' (or 'Equals') shadows an overridable method in the base class 'Object'. To override the base class method, this method must be declared 'Overrides'."
However, if I declare them as Overrides, I get the error "function 'GetHashCode' cannot be declared Overrides because it does not override a function in the base class."!!I am also getting a compiler error on the "Implements" line to the effect that I must implement "getHashCode" but I presume that is a result of the first problem.
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Oct 6, 2009
I have built a class to store profile information and there is another class that inherits System.Collections.CollectionBase that actually holds the data objects. Now the issue is when the page is refreshed the entire class is wiped off the map.
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Feb 18, 2010
I've lived in the VB6 world for the last 15 years and am only now starting to learn .NET. I've got a long way to go, but I am hung up on a fundamental issue about collections.I live and die by collections in VB6; I use them for just about everything I do.So I am very used to having the abilities that the intrinsic VB6 Collection has.Things like adding items with keys, referencing items by key or index, having the "Add" method return an instance of the object, being able to add custom procedures to the collection, having it strongly typed, etc.But all of the collection information I have read about in .NET doesn't really do all of this.(I am starting out in VB.NET, with the possibility of moving to C# at a later time, so i am trying to stay away from the Microsoft.VisualBasic namespace.)
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Mar 29, 2011
I built a custom class and collection for the class for an app that I'm creating. What would be the best way for me to store it so that it will be available on the next startup of the app? It's a pretty simple class with a few strings, etc.
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Dec 29, 2011
I know how to create custom controls with all sorts of properties, but I cannot get a collection property to work
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Oct 27, 2010
I have tried to write:
Event EventName(Of T)()
But Visual Studio tells me that "Type parameters cannot be specified on this declaration."
Is such a declaration possible or will I have to put T as a regular argument?
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Oct 5, 2011
I have a custom collection class. The main member of the class is a List(Of T). I did what this article says: [URl] For some reason though I can only foreach my collection once. The second time it tries it goes out of range because the position does not reset after the first foreach. What am I doing wrong?
[Code]...
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Jun 19, 2012
If i have an object that implements an interface (and don't know the exact object) i can call a sub (DoSomething) by going:
vb
Dim iObj = trycast(something, iInterface)
if iObj isnot nothing then
iObj.DoSomething()
end if
How can I do this for a Generic? such as...
vb
Public Class TestClass(of T)
Public sub DoSomething()
....
end class
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Aug 24, 2010
I would like to set up a custom app configuration element collection section like this
<logSectionGroup>
<logSection name="Testttt">
<properties name ="Pride">[code]....
Properties would be the configuration element, and log section would be the configuration element collection.The problem is, I've only seen where you can have multiple instances of a single element instead of multiple elements.
<Section name="Section1">
<Section name="Section1">
<SubSection name="SubSection1">[code]....
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Jul 6, 2009
During a code review I looked at set of repository classes (in vb.net). I am used to seeing these repository classes full of functions that return collections (among other things) of your domain objects. However, this repository had 1 public property and 1 private variable that looked something like this:
Private _item as Collection (of Customer)
Public Item as Collection (of Customer)
Get...
Set...
In the "Get", there is code that gets a the Customers from the DAL and loads it in the private _item. What would the benefits be in using a property (customerRepository.Item) instead of plain old function (customerRepository.GetAllCustomers)? The "Property" way looks odd to me but odd doesn't always mean wrong.
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