Singleton object doesn't detroy when i assign it to null. - C# Discussion Boards

AB777131-Jul-06 4:26

31-Jul-06 4:26

You have a point,
my solution will work only for the applications that connect to the database.

Thanks & Regards,
Pramod

Re: Product Registration and Keys

Ennis Ray Lynch, Jr.31-Jul-06 4:33

Ennis Ray Lynch, Jr.

31-Jul-06 4:33

Internet activation always works but it is wrong. Machine based authentication can be done with encypryption and the registry Unf, windows doesn't allow self modifying executables. However, you could also use a generated resource file.

I like to cripple my apps in such a manner as to allow full access but make it difficult to use professionally.

For more expensive applications there is always the hardware key.

A man said to the universe:
"Sir I exist!"
"However," replied the Universe, "The fact has not created in me A sense of obligation."

-- Stephen Crane

Re: Product Registration and Keys

LongRange.Shooter31-Jul-06 5:16

LongRange.Shooter

31-Jul-06 5:16

One thing that I've seen products do is they will create a dll in the Windows/System32 library that is actually a binary serialization of the data they need. They do a nice job of also picking a name that looks important. You are still vulnerable if they are running a product that allows the user to stop an application from writing to disk. I've seen demo products running for months because they could not write their DLL to the hard drive.

Re: Product Registration and Keys

Steve Maier31-Jul-06 7:32

Steve Maier

31-Jul-06 7:32

What about using the licensing system that is built into .NET? There is a free open source version that ties into that and works pretty well. Open License[^]

It allows you to set a date range or number of days that a license is valid. The app would then fail on coming up and you could tell in the main function that it was a license issue and prompt the user to get a new one or whatever you want.

Steve Maier, MCSD MCAD MCTS

Installer Dilemma!!

Willem_Le_Roux31-Jul-06 2:26

Willem_Le_Roux

31-Jul-06 2:26

Hi guys/gals!

I have a little problem with creating a MSI package. I have added the custom "Customer Information" dialog to my installation process, but I don't know where this information is written to. I want to use this information for display on my "About" box and maybe later for online registration proposes.

Can anybody help?

Willem Le Roux

Re: Installer Dilemma!!

LongRange.Shooter31-Jul-06 5:17

LongRange.Shooter

31-Jul-06 5:17

The information only exists in memory. You would have to write a custom installer action that gets the data passed to it, then the code would have to persist it.

Re: Installer Dilemma!! [modified]

Willem_Le_Roux1-Aug-06 0:45

Willem_Le_Roux

1-Aug-06 0:45

Okay

And now repeat in English please Laugh | :laugh:

Sorry mrCondor, but I have no idea what you are talking about... Yet. I played around with what I think your idea is, and it seems that I will have to write some other application (exe), DLL, script (js... preferably) or something like that to get the information and write it to the registry... somewhere... Perhaps?

Also, I toyed around in MS help and got some interesting goodies about Properties, USERNAME properties, COPANYNAME properties, UserSID properties, how all this gets written to the registry under the "InstallProperties" key and all sorts of tit-bits like that, but no example, no nothing. Frown | :(

Can anybody please steer me in a general direction? I have absolutly no idea where to start... Fooling a little feelish now! Unsure | :~

uhm he he he...

Willem Le Roux

Singleton object doesn't detroy when i assign it to null.

madhusri31-Jul-06 2:07

madhusri

31-Jul-06 2:07

Here is the code sample of sington class and their clients

<br />
public class single<br />
    {<br />
        public string str = "Hello";<br />
        private static single s = null;<br />
<br />
        private single()<br />
        {<br />
        }<br />
<br />
        public static single CreateInstance()<br />
        {<br />
            if (s == null)<br />
                s = new single();<br />
<br />
            return s;<br />
        }<br />
<br />
        public string Get()<br />
        {<br />
            return str;<br />
        }<br />
    }<br />
    class Program<br />
    {<br />
        static void Main(string[] args)<br />
        {<br />
            single i = single.CreateInstance();<br />
<br />
            string str1 = i.Get();<br />
            Console.WriteLine(str1);<br />
<br />
            i.str = "World";<br />
<br />
            i = null;<br />
            single j = single.CreateInstance();<br />
<br />
            string str2 = j.Get();<br />
            Console.WriteLine(str2);<br />
<br />
            j = single.CreateInstance();<br />
            j.str = "New";<br />
            string str3 = j.Get();<br />
            Console.WriteLine(str3);<br />
<br />
            <br />
        }<br />
    }<br />

Output::
Hello
World
New

But it should be
Hello
Hello
New

since we assigned i=null then the singleton must be destroyed and new instance should be created when j = single.CreateInstance(); executed right?

Thanks and Regards
Madhu

Re: Singleton object doesn't detroy when i assign it to null.

Ravi Bhavnani31-Jul-06 2:19

Ravi Bhavnani

31-Jul-06 2:19

No, since i is a local variable. You're just nulling your local reference of the singleton (which continues to exist).

/ravi

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Re: Singleton object doesn't detroy when i assign it to null.

leppie31-Jul-06 3:23

leppie

31-Jul-06 3:23

madhusri wrote:
since we assigned i=null then the singleton must be destroyed and new instance should be created when j = single.CreateInstance(); executed right?

No, that defeats the goal of the singleton pattern.

xacc.ide-0.2.0.50 - now with partial MSBuild support!

Re: Singleton object doesn't detroy when i assign it to null.

madhusri31-Jul-06 5:35

madhusri

31-Jul-06 5:35

Hi leppie,

When i = null is assigned, there are no reference pointers pointing to the singleton object. Hence if there is a GC, then the singleton object has to be deleted. In this case, next time an instance to the singleton object is created, it should be a new object again. But the old object is being retained and returned when i call createInstance() again.

Basically, when will the singleton object be destroyed from memory?

We understand that an object will be deleted if there are no references to that object or if the object is set to null. Is this right?

Thanks and Regards
Madhu

Not necessarily

Ennis Ray Lynch, Jr.31-Jul-06 7:42

Ennis Ray Lynch, Jr.

31-Jul-06 7:42

When all object references are removed it is scheduled for garbage collection. The first round of the GC does the clean up. The next time the GC runs it removes it. If you need to free resources implement the IDisposable method and call that before assigning null and then just don't worry about it.

A man said to the universe:
"Sir I exist!"
"However," replied the Universe, "The fact has not created in me A sense of obligation."

-- Stephen Crane

Re: Not necessarily

engsrini31-Jul-06 8:15

engsrini

31-Jul-06 8:15

Event we tried to GC the i object after assigning to null ie.

i=null;
GC.Collect();
Thread.Sleep(2000);// Waitin for some time to Collect the object i by GC

even this never destroyed the object.

The GC has to run twice

Ennis Ray Lynch, Jr.31-Jul-06 8:37

Ennis Ray Lynch, Jr.

31-Jul-06 8:37

And if custom memory management is so important you shouldn't be using C#.

A man said to the universe:
"Sir I exist!"
"However," replied the Universe, "The fact has not created in me A sense of obligation."

-- Stephen Crane

Re: Singleton object doesn't detroy when i assign it to null.

Colin Angus Mackay31-Jul-06 8:01

Colin Angus Mackay

31-Jul-06 8:01

madhusri wrote:
When i = null is assigned, there are no reference pointers pointing to the singleton object.

This is incorrect. The class you showed has a static reference to its one and only instance.

madhusri wrote:
But the old object is being retained and returned when i call createInstance() again.

And it manages this because something is holding a reference that the CreateInstance() method can pass back.

madhusri wrote:
We understand that an object will be deleted if there are no references to that object or if the object is set to null. Is this right?

The first part is correct. The second part is incorrect because you are not setting the object to null, not now, not ever. What you are doing is setting a reference to the object to null.

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Re: Singleton object doesn't detroy when i assign it to null.

engsrini31-Jul-06 8:23

engsrini

31-Jul-06 8:23

Now we understand. Out situation is like One exe will invoke function in 2 separate dlls using reflection. first exe loaded the dlls. those dlls create log object using CreateInstance(). suppose if the dll1 assigned the

logobject.Moudulename="First";  //Variable in log object <br />
logobject=null;<br />
GC.Collect();

then the exe unloaded this dll1 and try to access dll2 function which uses logobject instance, will the changes made by dll1 will be afected to dll2's Logobject? if yes means the logobjected is collected by GC right so it will be no longer available to dll2 rite?

Re: Singleton object doesn't detroy when i assign it to null.

V.31-Jul-06 4:10

31-Jul-06 4:10

I think you need to dispose the object out of memory.
Assigning null is no different then assigning a value. The object itself still exists.

I've found a living worth working for, but I haven't found work worth living for.

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Re: Singleton object doesn't detroy when i assign it to null.

Colin Angus Mackay31-Jul-06 5:15

Colin Angus Mackay

31-Jul-06 5:15

madhusri wrote:
since we assigned i=null then the singleton must be destroyed and new instance should be created when j = single.CreateInstance(); executed right?

Nope, wrong!

See this code from CreateInstance:

if (s == null)
s = new single();
return s;

What happens here is the one and only ever instance never to be repeated is created if it does not exist and stored in the static field called s. s is always returned. Nothing else ever assigns to s therefore the singleton pattern is maintained becuase you have ensured that there will only ever be one and only one ever instance of the object. This is the goal of the singleton, the behaviour you expect is at odds with the pattern you have chosen.

Ctrl + B in RichtextBox

AB777131-Jul-06 2:02

AB7771

31-Jul-06 2:02

I want to set the font style to Bold when the user clicks Control + B key combination,
How do i do that?

Thanks & Regards,
Pramod

Re: Ctrl + B in RichtextBox

stancrm31-Jul-06 2:16

stancrm

31-Jul-06 2:16

private void richTextBox1_KeyDown(object sender, System.Windows.Forms.KeyEventArgs e)
{
	if(e.KeyCode == Keys.B && e.Modifiers == Keys.Control)
	{
		this.richTextBox1.SelectionFont = new Font("Microsoft Sans Serif", 8, FontStyle.Bold);
	}
}

Re: Ctrl + B in RichtextBox

AB777131-Jul-06 2:24

AB7771

31-Jul-06 2:24

Thanks

Re: Ctrl + B in RichtextBox

Empires31-Jul-06 2:28

Empires

31-Jul-06 2:28

You could also maintain the font and do it like this:

if (e.KeyCode == Keys.B && e.Control)
{
richTextBox1.SelectionFont = new Font(
richTextBox1.SelectionFont,
richTextBox1.SelectionFont.Style ^ FontStyle.Bold
);

e.Handled = true;
}

Michael Francik
Empireland, Inc.

Re: Ctrl + B in RichtextBox

AB777131-Jul-06 2:59

AB7771

31-Jul-06 2:59

Everything is fine
but when i press Ctrl + I the cursor moves one tab ahead,
Why does this happen?
is Ctrl + I any pre-defined short cut for richtextbox.
i am working in VS 2005.

Thanks,
Pramod

Re: Ctrl + B in RichtextBox

AB777131-Jul-06 2:37

AB7771

31-Jul-06 2:37

Thanks for that can also tell me how can i insert a link to a Folder in a richtext box.

Pramod

Re: Ctrl + B in RichtextBox

stancrm31-Jul-06 3:27

stancrm

31-Jul-06 3:27

See this:
http://msdn2.microsoft.com/en-us/library/f591a55w.aspx

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.