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13-Apr-09 4:38

DaveyM69 wrote:
a string is a reference type that behaves like a value type

A string is simply immutable. Value types work best when they are immutable but they don't have to be.

Re: struct or class?

PIEBALDconsult13-Apr-09 5:14

PIEBALDconsult

13-Apr-09 5:14

Make them classes unless there's a good reason to make them structs.

Do you want the type to support null? -- Value types pretty much don't
Do you want to define operators for the type? -- I've found that operators make more sense on value types
Should the type be immutable? -- Value types generally tend toward immutability, but maybe that's due to operators

Re: struct or class?

Colin Angus Mackay13-Apr-09 5:22

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13-Apr-09 5:22

PIEBALDconsult wrote:
Should the type be immutable? -- Value types generally tend toward immutability, but maybe that's due to operators

I would say the immutability aspect is fairly neutral. If it is mutable then I'd strongly recommend a class as value types are not good at mutability. But if it is immutable, could go either way for me - It wouldn't be a strong factor in making a choice.

Sql Backup

nagendra.vk13-Apr-09 4:24

nagendra.vk

13-Apr-09 4:24

hi everybody

I want to take my database backup which is created in sql server 2000 in windows application using C#

so i have no network its an independent system

i want to display all sqlserver instances in combobox

without internet(Lan etc..) how can i take backup my database using c#

hope you help me

thanks in advance
nagendra...

Re: Sql Backup

Colin Angus Mackay13-Apr-09 4:43

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13-Apr-09 4:43

I don't know which bit you are needing help with. Listing the SQL Server instances or taking the backup.

You can use SMO (SQL Server Mangement Objects) to enumerate the available servers. http://msdn.microsoft.com/en-us/library/ms162169.aspx[^]

Since a SQL Backup can only be done to the machine that a SQL Server resides on a LAN isn't necessary. In fact, it won't make any difference since the backup file must be local to the SQL Server.

You can issue a backup command through the SqlCommand object in the .NET Framework and ExecuteNonQuery().

Handling Exceptions from another thread

Fayu13-Apr-09 4:02

Re: Handling Exceptions from another thread

13-Apr-09 4:02

I am having some issue handling an exception thrown in another thread in my UI. My question is how can I handle exceptions from another thread without syncronized the threads in the UI. I would prefer to sync the threads in the class where the method is called. Any suggestions?

Here is my code:

Localized fields

Test t = new Test();

Method that throws the exception

public class Test
{
     public void DoSomething()
     {
          throw new MyCustomException(this,EventArgs.Empty);
     }
}

The exception

public class MyCustomException : Exception
{
     ...
}

This is in the UI. Not multi-threaded

void CallException()
{
     try
     {
          t.DoSomething();
     }
     catch(MyCustomException ex)
     {
          lblMessage.Text = "error";
     }
}

This is also in the UI. Multi-threaded

void CallExceptionASync()
{
     Thread thrd;
     ThreadStart ts = (ThreadStart)delegate
     {
          t.DoSomething();
     };
     thrd = new Thread(ts);
     thrd.Start();
}

Fayu13-Apr-09 6:17

Re: Handling Exceptions from another thread

13-Apr-09 6:17

I have created a workaround but I am not satisfied with it. If anyone has a better suggestion please let me know. Here is the workaround:

void CallExceptionASync()
{
     Thread thrd;
     ThreadStart ts = (ThreadStart)delegate
     {
          try
          {
               t.DoSomething();
          }
          catch(MyCustomException ex)
          {
               this.lblMessage.Invoke((MethodInvokder)delegate()
               {
                    this.lblMessage.Text = ex.Message;
               });
          }
     }
}

Luc 64801113-Apr-09 7:22

Luc 648011

13-Apr-09 7:22

if the thread throws an exception, and the catch is to touch a GUI Control, then you need Control.Invoke, there is no way around that since that thread is not allowed to touch any Controls.

BTW: A BackgroundWorker has a Completed event which does the invoking automatically, and its event argument holds the exception that may have occurred.

Smile | :)

master window

EmZan13-Apr-09 3:20

13-Apr-09 3:20

i need to creat a windows application with many independent window usin the idea of master page in web development

i tried to use tab but its so bad

generaly i need one window that has a panel embedded into it
this panel contains all othe windows when selected from the main one

can any one auggest any idea??

Colin Angus Mackay13-Apr-09 3:50

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13-Apr-09 3:50

I don't see what was wrong with the tab, unless you didn't want to see the tabs.

Each panel should contain one control, a user control that you can define elsewhere. That keeps the code cleaner rather than throw all the controls in one form. Does that help?

EmZan13-Apr-09 4:48

13-Apr-09 4:48

the problem is that

1.when i load the program for the first time all tabs will be loaded
and may be many tabs i will not need

2.not every thing will be valid for atab

i need a centeralized application from one windo
or u can say master window as i described

thanks for ur reply Smile | :)

Colin Angus Mackay13-Apr-09 5:00

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13-Apr-09 5:00

You can dynamically add and remove tabs as you need them.

EmZan13-Apr-09 5:01

13-Apr-09 5:01

bad design i think Frown | :(

Colin Angus Mackay13-Apr-09 5:03

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13-Apr-09 5:03

Why? Internet explorer and Firefox do it all the time. As I recall, Firefox was lauded for having tabbed windows that you create and dismiss at will.

Fayu13-Apr-09 4:03

13-Apr-09 4:03

consider using MDI.

EmZan13-Apr-09 4:49

13-Apr-09 4:49

what is MDI ?

Fayu13-Apr-09 5:01

13-Apr-09 5:01

In visual studio 2005/2008, create new Item and select 'Mdi Partent'. This will create a toplevel form that can contain other forms.

EmZan13-Apr-09 5:11

13-Apr-09 5:11

aha i know it

but it opens a new window not creates an embedded window
openning many windows is my problem

Colin Angus Mackay13-Apr-09 5:01

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13-Apr-09 5:01

EmZan wrote:
what is MDI ?

Multi document interface. Allows you to have one master window with many child windows inside. Each child window acts like a regular window (can be minimised, maximised, moved around etc) but only within the confines of the containing window.

how to populate data from dataset into textbox

naveen20_513-Apr-09 2:50

naveen20_5

13-Apr-09 2:50

hello i have one problem . i had one frontend in which there are textboxes dropdown . i have to populate data from excelsheet . well i succeed in making connection. but my problem is this that at one time one row data is populated in front end and then i have to click save button. then second row from the excel sheet should populate in my front end automaticaly. is this possible with using dataset . if yes can u guide me how.

thz in advance

C# on Mac OS

satsumatable13-Apr-09 2:42

satsumatable

13-Apr-09 2:42

Hi
Is there any open source that supports C# based development on top Mac OS?.

Thanks in advance ...

Re: C# on Mac OS

Colin Angus Mackay13-Apr-09 2:45

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13-Apr-09 2:45

Does the Mono Project not support the Mac? I know it is primarily Linux based, but then so is MacOS these days.

Re: C# on Mac OS

satsumatable13-Apr-09 3:04

satsumatable

13-Apr-09 3:04

OK, i did guess the same. Seems there is a Windows support also.

Thanks anyway..

Multithreading in windows Service

avi_dadi200213-Apr-09 2:33

avi_dadi2002

13-Apr-09 2:33

Hello everybody,
Please help me and suggest me how to do this and also tell me if any disadvantages with this approach. Thanks in advance.

I've 10 to 15 ftp addresses and credentials to those ftpsites.Now i've some files which needs to be upload to those sites.My xml file has the information about all ftp site address, credentials ,listening directory(from where to pick the file to upload) and destination directory(where to upload a file) details.And here in each record in xml i've different different intervals(10mins, 15 mins , 60 mins.....). According to that interval i need to pick and upload that file to the respective ftp folder.

I wrote one windows service in that windows service i used thread concept to achieve this. but all my files are uploaded at a time.I tested with some console application.Please help me.Sombody told me don't use threads it will take more processor usage like that, and they suggested me use timer.Please help me, its very urgent to me.

Thanks in advance from my heart.

Avinash Smile | :)

Re: Multithreading in windows Service

Fayu13-Apr-09 4:07