C# Discussion Boards - CodeProject

Threading Question - Object in AsyncCompletedEventArgs

Jammer16-Mar-09 14:05

16-Mar-09 14:05

Hi,

I have a ReadOnlyObservableCollection<t></t> being returned in an AsyncCompletedEventArgs derived object. Is there any way in the get; accessor to automatically pass it back to the original thread without having to use the Dispatcher in the callback method?

At the moment I'm doing this:

        void SyncCompletedCallback(object sender, SyncJobCompleteCallbackEventArgs args)
        {
            Dispatcher.BeginInvoke(DispatcherPriority.Normal, (ThreadStart)delegate
            {
                ReadOnlyObservableCollection<synceditem> history = args.SyncJobHistory;
                HistoryView.ItemsSource = history;
            });
        }
</synceditem>

I'd rather let consumers have easy access to the collection like:

void SyncCompletedCallback(object sender, SyncJobCompleteCallbackEventArgs args)
{
    HistoryView.ItemsSource = args.SyncJobHistory;
}

Thanks,

Jammer
My Blog | Article(s)

Button to scroll MDI Parent FOrm [modified]

jameschristianii16-Mar-09 11:54

jameschristianii

16-Mar-09 11:54

I am working on a touch screen application and I am trying to add a button(s) that function as pageup/pagedown on a MDI Parent form with the child forms as the items to scroll.

I've spent entirely way too much time scouring the internet for a solution to this. I've tried multiple items that I thought would be the answer to no avail.

I really thought that this would be the answer:

SendMessage(this.Handle, WM_VSCROLL, (IntPtr) SB_PAGEDOWN, IntPtr.Zero);

I know I'm close, but then again, I could be way off!

Ideas?

Confused | :confused:

I guess no one has a solution for this...
For those who are wondering...

Given the scope of the project and the fact that I had to use a MDI parent and children (specs from customer)and buttons to scroll (touch screen app), I used a method to give the appearance of scrolling by setting the location of each form in a foreach loop. It moves the forms as if it were scrolling.

modified on Wednesday, March 18, 2009 9:22 AM

Object Wrapping and Event Subscription

Jammer16-Mar-09 11:28

Jammer

16-Mar-09 11:28

Hi All,

I'm just wrapping up some functionality in a class that uses some third party components under the hood. My wrapper object by default subscribes to some events on the third party components and forwards them on to consumers of my wrapper class.

In general I would expect consumers to subscribe to these events most of the time, however, I can't always assume that and I also want to optimise my wrapper. What is the general consensus on coding around this? At the moment I always subscribe to the third party events and then each time one of these events fires I check to see if the event handler is null before forwarding on the event.

Is there a better pattern for this?

Jammer
My Blog | Article(s)

Re: Object Wrapping and Event Subscription

Christian Graus16-Mar-09 12:37

Christian Graus

16-Mar-09 12:37

If you're using delegates, your choices are

1 - check if it's null and if so, do nothing and
2 - check if it's null and if so, throw an exception.

Depends on if you want to force your clients to subscribe to the specific event.

Christian Graus

Driven to the arms of OSX by Vista.

Re: Object Wrapping and Event Subscription

Jammer16-Mar-09 12:41

Jammer

16-Mar-09 12:41

Hi Christian,

I've already implemented option 1 as I didn't want to needlessly throw exceptions. Although I wasn't sure this was the best way.

Thanks,

Jammer
My Blog | Article(s)

Re: Object Wrapping and Event Subscription

DaveyM6916-Mar-09 12:49

DaveyM69

16-Mar-09 12:49

Another option... If the methods in the wrapped class that raise the events i.e.
OnSpecificEvent(MaybeDerivedEventArgs e)
are protected virtual, then you can override them and fire your own events from your override methods so the original events will never get fired, only yours.

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

How to Refreash an array list

soulidentities16-Mar-09 7:40

soulidentities

16-Mar-09 7:40

Hi all
Can anyone tell me how to refreash an array;
I mean lets assume an array with some values.
Now I just want to clear all the contents of array by clicking a button.
That button will have the code like array.refreash....something like that I dont know.
I dont want to clear the array by using for loop to putting all array address(0-20) null.
Is there any way to do it.

Pls reply me

Thanks Big Grin | :-D

Re: How to Refreash an array list

0x3c016-Mar-09 7:46

0x3c0

16-Mar-09 7:46

You're looking for the Array.Clear static method

Re: How to Refreash an array list

soulidentities16-Mar-09 8:01

soulidentities

16-Mar-09 8:01

thanks I got the ans

Re: How to Refreash an array list

Mohammad Dayyan16-Mar-09 9:44

Mohammad Dayyan

16-Mar-09 9:44

Was your meaning ~~refreash~~ refresh ? Confused | :confused:

Re: How to Refreash an array list

S K Y16-Mar-09 15:09

S K Y

16-Mar-09 15:09

foreach(object yourArrayItem in yourArray)
{
youArrayItem.remove();
}

A S E L A

C# and Excel

su_penguin16-Mar-09 6:42

su_penguin

16-Mar-09 6:42

Hello all,

Excel.Application excel = new Excel.Application();
Excel._Workbook book = new Excel._Workbook();
Excel._Worksheet sheet = new Excel._Worksheet();
Excel.Range range = new Excel.Range();

After adding a reference to the Excel Object Library in my VC# project, these few lines start the process of opening a 'new' workbook. But, how do you open a workbook that already exists?
I would like to point to the link to the existing book, if possible.

Thanks

Re: C# and Excel

Jimmanuel16-Mar-09 6:58

Jimmanuel

16-Mar-09 6:58

excel.Workbooks should have an Open(...) method in it.

Re: C# and Excel

su_penguin16-Mar-09 7:01

su_penguin

16-Mar-09 7:01

THANK YOU!!!

Re: C# and Excel

Jimmanuel16-Mar-09 7:44

Jimmanuel

16-Mar-09 7:44

You're welcome. Smile | :)

Re: C# and Excel

su_penguin16-Mar-09 8:15

su_penguin

16-Mar-09 8:15

This method really stinks. Why is this in the object model? http://msdn.microsoft.com/en-us/library/bb179167.aspx

Thanks

Re: C# and Excel

Jimmanuel16-Mar-09 8:49

Jimmanuel

16-Mar-09 8:49

it's there so you can open existing workbooks Smile | :)

. I'm not sure about the 2007 version, but with the Office XP version you can get away with passing in System.Reflection.Missing.Value for all the parameters except the first one - provided that you don't care what those params are.

c# class editor

MikiR16-Mar-09 6:24

MikiR

16-Mar-09 6:24

Hello,
I'm trying to create an application, using c#, that takes a .cs source file, parses it (I just need to extract class name, methods, properties, structs, enums) and then lets the user to perform some operations like add new method, delete a method or insert some line of code in an existing method.
At the moment to achieve it, I use a parser library (NRefactory from SharpDevelop) and then I thought to perform these operations using CodeDom functions.
But using CodeDom it's painful!! Is there any other library that I could use?
Is the method I described (NRefactory + CodeDom) the best way or is there something else I should try?

Thanks

Re: c# class editor

led mike16-Mar-09 6:59

led mike

16-Mar-09 6:59

MikiR wrote:
the best way

Best in comparison to what? Measuring with what criteria?

Your question, or lack of one, suggests you might be better served focusing on getting something, anything to work.

Re: c# class editor

MikiR16-Mar-09 7:10

MikiR

16-Mar-09 7:10

Ok, forget "best way" phrase. It's the worst expression I ever used and
trust me, I'll never use it in my life! I promise!!

Now..Can I have an answer about my problem? It's there an easy ("easy" in comparison to what?) way (some libray, some helper class) that help me to use CodeDom to inserting piece of code, adding/removing methods to an already parsed c# class?

Accessing a Web.config from a windows app [modified]

dptalt16-Mar-09 5:28

dptalt

16-Mar-09 5:28

How can I read a connection string in web.config file from a windows app?
The ConfigurationManager.ConnectionStrings is not available from a windows project.

modified on Monday, March 16, 2009 12:07 PM

Re: Accessing a Web.config from a windows app

led mike16-Mar-09 5:42

led mike

16-Mar-09 5:42

dptalt wrote:
How can I accesses a web.config from a windows app?

From your post it is not clear what the technical problem is, nor what your question really is.

web.config is a file. Do you not know how to open a file?

Open SQL connection via C#

Ido16-Mar-09 4:44

Ido

16-Mar-09 4:44

Hi,
I am working under C# 2008 and SQL 2005 express edition.

To connect to database I used with Typed Dataset and all insert command I used with same object. I had over million rows.

At this object I implement Insert command. I glance in “TypedDataset.Designer.cs” file under my Typed Dataset at Insert command and see that Adapter open and close the connection after each insert execution.

My questions are:

1. This is necessary to open and close the connection all the time?

2. We cannot to leave the connection open?

3. What about performance?

4. There is another way to insert large quantities of rows to database?

Thanks,
Ido

Re: Open SQL connection via C#

led mike16-Mar-09 5:39

led mike

16-Mar-09 5:39

Most modern database+platform systems use connection pooling[^] so the connection is not actually opened and closed each time.

Re: Open SQL connection via C#

Ido16-Mar-09 6:36

Ido

16-Mar-09 6:36

hi,
Thanks.
so, the behavior is normally in spite of that i see on SQL Server Profiler Audit Login Audit Logout for each execution?

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