.net - What Is The Optimal Approach To A WithEvents Collection
Mar 5, 2010
What is the optimal approach to a WithEvents Collection - VB.NET?Have you any remarks on the code bellow (skipping the Nothing verifications)?The problem is when I obtain the LinkedListNode(Of Foo) in a For Each block I can set myNode.Value = something, and here is a handlers leak...
-Could I override the FooCollection's GetEnumerator in this case?
-No. :( cause NotInheritable Class LinkedListNode(Of T)
Class Foo
[code]....
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Mar 23, 2011
How do you decide what the optimal value for MaxDegreeOfParallelism is for any given algorithm? What are the factors to consider and what are the trade-offs?
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Feb 10, 2011
My application needs to be a service (it needs run regardless of whether a user is logged on), but I also need some sort of client control/oversight over what it is doing. What is the optimal way to do this?Write a separate application to communicate with the service application - I see that as best solution in terms of stability, since the applications will be decoupled somewhat Use callbacks on system events in the service application to load UI forms directly from the service application - I see this as being easier to deploy.
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Feb 21, 2010
I'm writing a windows application and I've hit a bit of a roadblock. It wouldn't be a difficult program, except that I'd like to support more than one user and with each user I need to have many, many different settings change instead of, say, two or three. I'm wondering if there's a standard ideal way of storing large amounts of settings for different users?
I'll try to describe what I'm trying to do here..At the moment I have an Access database (for easy deployment) with about 60-something tables. 66 tables are named after books, and each have a different number of chapters. Each of those tables contains one row for every chapter plus a CheckState field that contains a 0 or a 1. I also have a simple Users table with a UserName and UserID field, and another AllBooks table with data for every book, like the name and the number of chapters.
When I user is selected, I have a listbox that displays every book (taken from the AllBooks table) and then a checkedlistbox that displays the chapters of the selected book and automatically checks off different boxes depending on the CheckState field.
So but I'm a bit stumped on how to implement different users... instead of tons and tons of different tables should I have a different table for each user that have 60-something columns...? I dont know enough about relational databases to make the right call.
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Oct 5, 2011
Is there any way of getting the monitors optimal resolution in vb?
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Oct 22, 2009
I am looking for some guidance with the most optimal or efficient way to export a dataset to an excel file. I have searched the forums and found a number of methods to do this. However, the code I am currently using is very inefficient as it is itterating through the rows and columns to create the excel file. The app I am working on needs to be able to create 50 or so excel files each with 500+ rows and 40-50 columns. This method seems to inefficient for my use
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Mar 14, 2011
I just want to know, What parameters or attributes should be taken in connection string so as to handle high traffic enterprise applications? Like in general we use server, initial catalog, userid, passwd. Some times we add timeout , and in some scenario pool etc. But i don't know what attributes should i take in as my common practice apart from above.
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Oct 29, 2011
I am looking for some guidance with the most optimal or efficient way to export a dataset to an excel file. I have searched the forums and found a number of methods to do this. However, the code I am currently using is very inefficient as it is itterating through the rows and columns to create the excel file. The app I am working on needs to be able to create 50 or so excel files each with 500+ rows and 40-50 columns. This method seems to inefficient for my use.
I have seen some code out there to use an ODBC call to excel to create the file. I am wondering if someone can verify that this is the most efficient way to meet my goal. It should also be noted that after the export I will want to do some basic formatting of the sheet. Adding bold column headers, autofilters, and autofit all columns.
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May 30, 2012
I am working on a realtime application where the data is addded to a List(of T) all the time. MB per minute
Elements older than X minutes shall be removed from the beginning of the list to free memory.
As far as i can understand will there be an internal (slow) redim when i add each element after i have reach the number defined with the Capasity metod. (I set that quite big from the start, but the data speed is unpredictable so it can be exceed)
What happens each time i remove and element from the beginning of the list , seems like it takes a lot of time, ? new redim ?
What is the most CPU fficient way of removing 1 or many elements from the beginning of such a list?
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Jan 15, 2010
Is it good practice to store sub-collections of item X inside a parent collection of item X for caching 'filter-queries' which are performed on the parent collection? (They won't be used together (as in color AND type).) Or is it also ok to just Loop over the collection and return the correct entities in a temporary collection?
[Code]...
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Dec 15, 2011
OK, I have this loop I want to perform which involves the serial port. Not to get too specific I'm actually sending data to an external device within a loop The loop involves a Start number, increments by a Step and ends when it gets to Stop This repeats until I click a STOP button.
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Sep 7, 2011
I have the following classes:
Product, Service and OrderItem
Product and Service must inherit OrderItem. So basically I want to store OrderItem object in my shopping cart and these object are store in a list.
Public MustInherit Class OrderItem
Private m_enuItemType As TypeOfItem = TypeOfItem.None
Private m_strUserID As Integer[code].....
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Jul 28, 2009
I understand that there are several ways of Inserting, Updating and Deleting records in a database such as DataAdapters, DataSets, TableAdapters, SqlCommandBuilders, Parameterized SqlCommands, StoredProcedures, etc, etc,etc. According to David Sceppa Sprocs are the most preferred. Ok, I go with him on this one (who am I to challenge him anyway?).
My question is, apart from Sprocs, which of these options is the BEST for a large commercial database application and why, taking performance into account? What are the benefits and drawbacks of each option?
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Jul 18, 2009
I am writing a program to assist Paramedic students in learning the Drugs that they have to know in order to pass their classes. I have created an Access database to hold all the information on these drugs, but not every student that will use this program will need to learn all the drugs contained within this database.
Right now I have 43 drugs in the database and still growing.
What I want to do is to present to the student the drugs and have them say "Y" or "N" as to whether its on their required list to learn. That way they only work on the ones that they need to.
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May 18, 2012
I've two BGW with similar coding but different approach, My second BGW shows me "NOT RESPONDING" whenever i try move/click/focus to form while the BGW is running.
VB
RichTextBox2.AppendText("Some Text")
process2.ReportProgress(inc)
My.Computer.Network.DownloadFile(andpic, "pics/" & spliti(0) & nnum & ".png")
My.Computer.Network.UploadFile("pics/" & spliti(0) & nnum & ".png", "ftp://ftp.mywebsite.com/domains/mywebsite/public_html/Pics/" & spliti(0) & nnum & ".png", "users", "password")
WebBrowser1.Navigate("Mywebsite")
I've taken out number of things that i think is causing this error Are they the cause of "NOT RESPONDING" ?
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Nov 12, 2010
To write a effecient Active Directory library to ease the work of technicals who are responsible to create access models into the domain controller's Active Directory. This library must allow the following:Basic operations: Add, Modify, Delete, List entries;An entry may either be an organizational unit, group or user (no further need required as of now);I thought about having a class which would represent the domain with which we want to work with.
public class Domain {
public Domain(string root) {
Root = root;
[code].....
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Aug 26, 2009
I have a database with three tables:
stock
orders
order_details
Stock and Orders are self explanatory. Order_details is a lookup table, holding basically just the orderID, stockID and quantity for each item in the order. That's not very friendly for the user however, so what I want to show is a DataGridView with some elements from order_details, and some from stock, i.e.:
Part_Code, Item_Name, Description, Quantity, Price
I can create a database view for this easily enough, and bind it to a datagridview. It shows existing items in the order fine, but the problem is the view doesn't update when I add new elements to order_details in the dataset. It appears that it's bound to the main database, and so won't update until I save the record. That also has the problem that it's now much harder to update the database. A simple datagridview bound to order_details would make it easy for the user to enter quantities and for me to save the record, this one now needs a custom update statement.
In summary:
- I want to show data from two tables
- I want the datagridview editable (well, the quantity column anyway)
- I want the datagridview to update when I add entries in the dataset
What is the best/easiest way to do this? Is my current approach of a view in the database and custom update statements sensible? How can I get the datagridview to refresh whenever there's a change to the local dataset?
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Jul 24, 2009
I recently started a project and needed to do some integration with LDAP via DirectoryServices. I've done this in other apps so I went into one of them to see how I did it -- why reinvent the wheel right? Well, while this wheel works, it was developed years ago and kinda smells (it's wooden, firmly attached to the previous vehicle, hard to repair and produces a potentially bumpy ride).So I thought to myself, this is the perfect time to refactor this puppy and make it more portable, reusable, reliable, easier to configure etc. Now that's fine and dandy, but then I started feeling a tad overwhelmed regarding to where to start. Should it be a separate library? How should it be configured? Should it use IoC? DI?
So my [admittedly subjective] question is this -- given a relatively small, but quite useful class like the one below, what is a good approach to refactoring it? What questions do you ask and how do you decide what to implement or not implement? Where do you draw the line regarding configuration flexibility? [Note: Please don't bash this code too much okay? It was written a long time ago and has functioned perfectly well baked into an in house application.]
Public Shared Function AuthenticateUser(ByVal id As String, ByVal password As String) As Boolean
Dim path As String = GetUserPath(id)
[code]......
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Apr 11, 2010
I'm working on a system where there can be 2 level of users "Admin" or "Researcher".We have the requirement to allow the researcher to change fields for a record a record, but they want the original values to stay in the record and have an admin "accept" or "approve" the changes before the real record gets updated.Has anyone run into this scenario before? I'm trying to think of the best way to do this.
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Oct 15, 2009
Trying to implement a recordset approach in VB.NET and have gotten to the point where things almost run. :)
Code:
Dim strSQL As String
Dim rsMaster As New ADODB.Recordset
strSQL = "select * " & "from tblDQ " & "order by xid, xcode, xDOS"
[Code].....
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Mar 25, 2012
I'm currently working on a system that requires monthly, quarterly and annual reports. I have no problem in generating/retrieving the data, my problem is the presentation. What is the best way to do it? I need the report to be:
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Jun 16, 2010
I have a wierd problem with threading in an ASP.NET application. For some reason, when I run the code in the request thread, everything works as expected. But when I run it in a separate thread, nothing happens.This is verified by calling the below handler with the three flags "on", "off" and "larma" respectively - in the two first cases everything works, but in the latter nothing happens.[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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Dec 17, 2009
Who knows, why in vb.net WinForm projects the designer by default use the Friend WithEvents attributes and in C# - private ones.
By ex, in a form.designer.
.cs
private Label Label1;
.vb
Friend WithEvents Label1 as Label;
For WithEvents is more or less clear(for using Handles, apparently). But why Friend in VB and private in C#...
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Jul 11, 2011
i have the folowing co
For x = 0 To 7 Step 1
For i = 0 To 7 Step 1
Dim rectangleShape1 As New Microsoft.VisualBasic.PowerPacks.RectangleShape() 'create a new object to assign to the array location
board(x, i) = New Microsoft.VisualBasic.PowerPacks.RectangleShape() 'create the new object in the array
[code].....
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Feb 11, 2010
When you declare an object 'WithEvents' and then utilize the "Handles" clause at the end of your event methods, how does Visual Basic manage a reference change for the object? In other words, if the withevents var is set to ObjectA, then later I switch it to ObjectB (or nothing), does Visual Basic automatically both remove those handler methods from ObjectA, and attach them to ObjectB? Or do I still have a ObjectA's events being handled behind the scenes?
I ask this because if instead you use AddHandler for an object, and then switch your reference, unless you removed the handler before switching, your original object is still handled (at least I'm pretty sure that's how it works).
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Apr 21, 2010
I have the following classes: Public Class Email
[Code]...
If a create a wrong email lets say "email" the exception is correctly cached and a message is showed however is i input a valid email the event is not raised, the object is being created but no message is shown and no error or exception is thrown i suspect it has something to do with using "myemail = new Email(email)" but i have seen examples of using new with withevents with no problem.
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May 17, 2010
Does anyone know why a local variable cannot be declared WithEvents?T
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Jun 9, 2011
I'm trying to create multiple instances of a child form. This form has an event that feeds a string variable back to the parent so I'm declaring it with WithEvents which is declared outside of the Sub - meaning multiple clicks will not open multiple forms.
another method of doing this while keeping the event?:
Dim WithEvents FRestoreDB As New FormRestoreDB()
Private Sub BtnOpenDB_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnOpenDB.Click
[Code].....
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Feb 24, 2010
Is it necessary to set to Nothing(in Dispose()) all WithEvents fields?
Apparently Handles keyword adds handlers to such fields, but does not remove it until this field is not Nothing, and this can generate memory leaks?!.
This should be specially actual on cases like
class Foo
{
Private WithEvents _bar as Bar
[Code].....
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