C# Discussion Boards - CodeProject

Re: Copy Object In Memory

19-Dec-06 22:53

I've been looking around for a while, and i've found the Marshal.Copy() function, but that's not really what i'm looking for.

Is there any way to actualy copy a managed object in memory, as opposed to instantiating a new one? I don't really want to enter the realms of unmanaged copying, unless i can drop the unmanaged reference at the end of the copy function.

Any thoughts?

cheers

Tris

Bekjong19-Dec-06 23:33

Bekjong

19-Dec-06 23:33

Why not serialize your object into a memorystream?

Standards are great! Everybody should have one!

Re: Copy Object In Memory

Tristan Rhodes20-Dec-06 0:30

Re: Copy Object In Memory

20-Dec-06 0:30

I looked at it, but its too expensive. I just want to copy the memory footprint wherever the object is and get a pointer / reference to that object.

Serialization is a pretty expensive procedure and i'm really looking at this for creating objects faster than using a constructor.

Might look at copying byte arrays tho.

Cheers

Tris

Bekjong20-Dec-06 1:22

Bekjong

20-Dec-06 1:22

I think you'll have to go for unmanaged code if you want it to perform. But I'm no expert. I found this piece of code to clone objects once, but I don't think it performs very well either.

static class Cloner
    {
        public delegate object CloneDelegate(object o);

        private static CloneDelegate cloner;

        public static T Clone<T>(T o)
        {
            if (cloner == null)
            {
                MethodInfo info = typeof(object).GetMethod("MemberwiseClone",
                    BindingFlags.Instance | BindingFlags.NonPublic);

                cloner = (CloneDelegate)
                    Delegate.CreateDelegate(typeof(CloneDelegate), null, info);
                Debug.Assert(cloner != null);
            }

            return (T)cloner(o);
        }
    }

Standards are great! Everybody should have one!

DataGridView with a RichTextBox Column (read only)

fatamos19-Dec-06 22:47

fatamos

19-Dec-06 22:47

Can anyone point me in the right direction for declaring a RichTextBox column within a DataGridView...

I know there are a few examples revolving around the Calander control... but... these examples all revolve around editable controls... the displayed control remains a TextBox until it is clicked... which is no good for me... as I want to display each cell as a RichTextBox.

I assume my only option is to derive from DataGridViewCell and override Paint... but my c# is little weak and I'm struggling.

In addition, I may be using a hammer to crack a nut... as all I want to do is to display text in a column which may have some words underlined... from my limited understanding of .net controls... I can only do partial underline with a RichTextBox... thus the need to create a RichTextBox column.

Thanks for anyone who actually reads this... and a double thanks for anyone who replies.
Smile | :)

Re: DataGridView with a RichTextBox Column (read only)

mrwisdom17-Dec-08 20:45

mrwisdom

17-Dec-08 20:45

http://www.codeproject.com/KB/cs/RtfInDataGridView.aspx[^]

C# Newbie needs help with Error

wedtm19-Dec-06 22:47

wedtm

19-Dec-06 22:47

Okay, I have this function that I want to run, it's pretty simple, but for the life of me, It's not working, can someone take a look at it and let me know what you think? It's like connectionStr never gets set, yet the way I call it is MysqlNonQuery("SELECT * FROM account", 1);

<br />
using System;<br />
using System.Collections.Generic;<br />
using System.Text;<br />
using MySql.Data.MySqlClient;<br />
<br />
namespace mangosAdmin<br />
{<br />
    class functions<br />
    {<br />
        public static string MysqlNonQuery(string sql, int db)<br />
        {<br />
            string connectionStr;<br />
            <br />
            if (db == 1) // Select 1 for mangos DB<br />
            {<br />
                connectionStr = "Database:" + Properties.Settings.Default.mangosDB + ";Source=" + Properties.Settings.Default.mangosHost + ";User Id=" + Properties.Settings.Default.mangosUser + ";Password=" + Properties.Settings.Default.mangosPass;<br />
            }<br />
            else if (db == 2) // Select 2 for Realm DB<br />
            {<br />
                connectionStr = "Database:" + Properties.Settings.Default.realmDB + ";Source=" + Properties.Settings.Default.realmHost + ";User Id=" + Properties.Settings.Default.realmUser + ";Password=" + Properties.Settings.Default.realmPass;<br />
            }<br />
            else<br />
            {<br />
                connectionStr = "Database:" + Properties.Settings.Default.mangosDB + ";Source=" + Properties.Settings.Default.mangosHost + ";User Id=" + Properties.Settings.Default.mangosUser + ";Password=" + Properties.Settings.Default.mangosPass;<br />
            }<br />
            try<br />
            {<br />
                MySqlConnection myConnection = new MySqlConnection(connectionStr);<br />
                MySqlCommand myCommand = new MySqlCommand(sql);<br />
                myCommand.Connection = myConnection;<br />
                myConnection.Open();<br />
                myCommand.ExecuteNonQuery();<br />
                myCommand.Connection.Close();<br />
            }<br />
            catch (MySqlException ex)<br />
            {<br />
                return(ex.Number+ex.Message);<br />
            }<br />
<br />
            return ("0");<br />
            <br />
<br />
        }<br />
<br />
        <br />
    }<br />
}<br />

Re: C# Newbie needs help with Error [modified]

althamda19-Dec-06 23:04

althamda

19-Dec-06 23:04

What's the actual error that you're getting from your code?

Error?!!

Nafiseh Salmani19-Dec-06 22:10

Nafiseh Salmani

19-Dec-06 22:10

i encrypt my database(access) and when my project is running , the database is decrypt and copy on system32 , and after that when the project is closing i delete the database on system32 folder .

it is ok on my computer , but when i run it on another computer , the db decrypt successfully , but in one of my function which i use connection.open , show following error :

could not use ;file already in use

how could i solve this error?!!!

Guffa19-Dec-06 22:26

Guffa

19-Dec-06 22:26

Make sure that the method that creates the file closes it properly.

---
It's amazing to see how much work some people will go through just to avoid a little bit of work.

Nafiseh Salmani19-Dec-06 23:37

Nafiseh Salmani

19-Dec-06 23:37

if that method dosn't close it, why there is not any problem on my computer?

Guffa20-Dec-06 1:47

Guffa

20-Dec-06 1:47

There can be many different reasons why code that is not completely correct may work in one place but not another.

Among possible reason can be different file systems, different memory load, different cpu load, different operating systems.

---
It's amazing to see how much work some people will go through just to avoid a little bit of work.

Dave Kreskowiak20-Dec-06 6:02

Dave Kreskowiak

20-Dec-06 6:02

You said you're putting this database in the \Windows\System32 folder? Did it occur to you that not every user account has full access to that SYSTEM folder? You might want to pick a better place to put that database before you try and access it, like in the root of the Users profile or in the Temp folder. Even if all you're doing is querying the Access database and not making any changes to it, you still need full read/write permissions to the FOLDER that the .MDB file is in.

And for why it works on your dev machine and not on others - did you develop your app under an Admin account?? Not a good idea - even though most developers do this...

Dave Kreskowiak
Microsoft MVP - Visual Basic

Invoking events on a different thread...

Nafiseh Salmani21-Dec-06 23:19

Nafiseh Salmani

21-Dec-06 23:19

both computer have the same os , and i login as admin in both computer so it is not for permission .

Shy Agam19-Dec-06 22:03

Shy Agam

19-Dec-06 22:03

Hi,

I have a class which uses async sockets functions (i.e. BeginXXX).
One of the functions in my class for example is Listen().
In my callback functions I would like to fire events.
These events could sometimes be used to control the UI.
So what I'm looking for is a way to invoke the events on the calling thread instead of the callback's thread.
I thought of holding a reference to a Control object inside my class.
This reference would be sent to my class through the constructor, and I could then call Invoke() on it.
But what if its not a Control which called my Listen() function?

Is there any way to know which thread is the calling thread, and invoking the events on it?

Thanks in advance,
Shy.

Tristan Rhodes20-Dec-06 0:41

20-Dec-06 0:41

Hi Shy,

You can't really invoke the callback function on the calling thread, as that would have to be invoked Synchronously.

I'm assuming the reason you are trying to do this is because you can only manipulate GUI components from the thread they were created on (Static compartment). If this is the case, then you don't need to worry about using the calling thread to throw the events.

Instead, raise the events, and supply a delegate to the application Form, Form.Invoke(myDelegate)

This will run whatever code you need executing on the forms creating thread which will do any UI manipulations you need.

If that's not what you wanted, shout back and i'll have another look.

Tris

Shy Agam20-Dec-06 2:16

Shy Agam

20-Dec-06 2:16

Tristan Rhodes wrote:
Instead, raise the events, and supply a delegate to the application Form, Form.Invoke(myDelegate)

Hmm... Not really sure what you mean...
Could you please give me an example?

In the meanwhile, I did the following, but I'm not really sure this is the right way:

class TCPSocket
{
    public event ConnectedEventHandler Connected;

    private Control user;

    public TCPSocket(...) { ... }

    public TCPSocket(..., Control user)
    {
        ...
        this.user = user;
    }

    private void RaiseConnectedEvent(IPEndPoint ep)
    {
        if (Connected != null)
        {
            if (user != null)
                user.Invoke(Connected, ep);
            else
                Connected(ep);
        }
    }
}

In my callbacks I use my RaiseXXXEvent() methods.
So basically this is how I invoke all of my events...
I'd be glad to hear your opinion about my code... Smile | :)

Is there something wrong with what I'm doing?

Tristan Rhodes20-Dec-06 2:30

20-Dec-06 2:30

Hi Shy,

I think the layouts a bit skewed.

You shouldn't really need to supply the control if the control can subscribe to the event.

try just using:

<br />
	private void RaiseConnectedEvent(IPEndPoint ep)<br />
	{<br />
		if (Connected != null)<br />
		{<br />
		Connected(ep);<br />
		}<br />
	}<br />

Then subscribe the relevant form to the event

<br />
class MyForm<br />
{<br />
	TCPSocket socket;<br />
	Control myControl;<br />
<br />
	// Handles socket.Connected event<br />
	private void SocketEventHandler(object sender, SocketEventArgs e)<br />
	{<br />
    // Handle Here (This will run on the executing thread NOT the GUI thread)<br />
<br />
    // Add the RunGuiThing delegate to the form invoker, this will<br />
    // run the desired delegate on the form / control creation thread.<br />
    me.Invoke(RunGuiThing);<br />
  }<br />
<br />
// GUI Handler<br />
  private void RunGuiThing()<br />
  {<br />
    // Update GUI control things here (This will be run on the GUI thread)<br />
    myControl.BackgroundColor = Color.Green;<br />
  }<br />
}<br />
<br />

Hope that solves it

Tris