Re: Copy Constructor - C# Discussion Boards

25-Jul-02 10:57

So it's C# after all?

See the docs for SetWindowsHookEx here:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winui/winui/windowsuserinterface/windowing/hooks/hookreference/hookfunctions/setwindowshookex.asp[^]

the hMod (third) parameter contains the module handle of the module (EXE or DLL, must be DLL if systemwide) that contains the hook procedure.

I'd recommend you to write the DLL with the hook function in straigth Win32 SDK code, so it is smaller (imagine having to load all .NET runtimes in every process??) Export two routines to start and stop the hook, and from the hook procedure you could send a message to your app's window (written in C#).

-- LuisR

──────────────
  Luis Alonso Ramos
  Chihuahua, Mexico
  www.luisalonsoramos.com

"Do not worry about your difficulties in mathematics, I assure you that mine are greater." -- Albert Einstein

Copy Constructor

Johnny Zee24-Jul-02 16:54

Johnny Zee

24-Jul-02 16:54

Anybody can help me how can I implement C++ Copy Constructor in C# with a generic example.

Thanks in advance

James T. Johnson24-Jul-02 18:08

24-Jul-02 18:08

You do it just like you would with C++; however the more correct method is to implement the ICloneable interface.

class Foo : ICloneable
{
  public int bar;
  public SomeClass baz;
  
  public Foo()
  {
    bar = 0;
    baz = new SomeClass();
  }
  
  public Foo(Foo sourceCopy)
  {
    bar = sourceCopy.bar;
    baz = sourceCopy.baz; // <- be careful see Clone method
  }
  
  public Foo Clone()
  {
    Foo f = new Foo();
    f.bar = bar;
    f.baz = new SomeClass();
    // Perform operations on f.baz
    // so that its state is the same as
    // this.baz
  
    return f;
  }

  object ICloneable.Clone()
  {
     return Clone(); // Call the strongly-typed
     // Clone method
  }
}

James
"Java is free - and worth every penny." - Christian Graus

Johnny Zee25-Jul-02 2:27

Johnny Zee

25-Jul-02 2:27

Thanks James you are always a good resource.

albean28-Jul-02 14:22

albean

28-Jul-02 14:22

Hi,

I was wondering if the the Clone() method in the Foo class needs to be public. I've been using C# now for about 10 minutes,;P so please forgive me if this is a dumb question.

Thanks.

James T. Johnson28-Jul-02 16:01

Re: ConfigurationSettings

28-Jul-02 16:01

Its not a dumb question at all because the answer isn't obvious.

In the Foo class there are two different implementations of Clone(), one which is a member of the class and the other is Foo's implementation of ICloneable.

Interfaces in C# (and .NET) require that their members be public; so when I specifically implemented the Clone method as Foo's implementation of ICloneable I didn't need to specify the public access modifier.

In C# there are two different ways to implement an interface.

The first method is by adding a public member for each item in the interface you are implementing. Most people probably use this technique to implement an interface.

interface IBar
{
  object Bar();
}
 
class Foo : IBar
{
  ....
  
  public object Bar()
  {
     ....
  }
}

The second method is to specify in the member's signature what interface it is implementing.

class Baz : IBar
{
  ...
 
  object IBar.Bar()
  {
    ....
  }
}

Unlike the first method the only way to use this member is cast the object to the interface (IBar ib = (IBar) myBaz;). Now you can use the member as if it were any other interface.

This also gives an advantage for the users of your class. You can provide two different implementations of a member: one to be used when dealing with the interface, the other to be used when dealing with the class itself.

Most of the collections in the .NET class library do this to provide a strongly-typed collection while also implementing the generic interfaces that provide a standard way of using a collection.

Hope that answers your question

James
"Java is free - and worth every penny." - Christian Graus

ConfigurationSettings

Steve Severance24-Jul-02 13:12

Steve Severance

24-Jul-02 13:12

I am trying to read a custom config section but its not working. ConfigurationSetting.GetConfig() returns null;
CONFIG FILE:
<configuration>
<configSections>
<section name="data" type="System.Configuration.SingleTagSectionHandler"/>
</configSections>

<data Server="GODSWORKSTATION" Username="MedWizard" Password="MedWizard" Security="SSPI"
PersistSecurity="false" Pooling="false" MinPool="20" MaxPool="1000" NetworkLibrary="dbmssocn"/>
</configuration>

CODE:
IDictionary valueTable = (IDictionary)ConfigurationSettings.GetConfig("data");

string Server = (string)valueTable["Server"];
string Username = (string)valueTable["Username"];
string Password = (string)valueTable["Password"];
string Encrypt = (string)valueTable["Encrypt"];
string Security = (string)valueTable["Security"];

Any ideas? Thanks.

Steve

Not all who wander are lost...

James T. Johnson24-Jul-02 16:18

Re: ConfigurationSettings

24-Jul-02 16:18

You need to change the section line to specify the full assembly name (since the assembly has a strong name this means the typename, the assembly name, version, and public key token).

<section name="data" type="System.Configuration.SingleTagSectionHandler, System, Version=1.0.3300.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>

I have an article that's done but needs formatting and proofreading before I post it.

James
"Java is free - and worth every penny." - Christian Graus

jparsons25-Jul-02 2:45

jparsons

25-Jul-02 2:45

I'm getting a 404 on your article.

Jared
jparsons@jparsons.org
www.prism.gatech.edu/~gte477n

Re: ConfigurationSettings

James T. Johnson25-Jul-02 2:50

25-Jul-02 2:50

Oops

it should have been configurationhandler not section Smile | :)

Correct link[^]

James
"Java is free - and worth every penny." - Christian Graus

Namespace Hell

stephen woolhead24-Jul-02 13:12

stephen woolhead

24-Jul-02 13:12

I have a c# project that is causing me problems at the moment.

I have a file that looks like this

------------

using System ;

namespace MyNameSpace.System
{
public class Test
{
public Test ()
{
System.Diagnostics.Trace.Writeline ("Hello World!") ;
}
}
}

------------

the problem is that when I compile this it VS complains that the namespace Diagnostics does not exist in MyNameSpace.System

Also when I type System. the intelisense gives me a choice of 'Test' only i.e. my clases in the MyNameSpace.System namespace.

if I change the line to
Diagnostics.Trace.Writeline ("Hello World!")
dropping the System it all compiles.

Is this normal namespace behaviour? If not (hope not as this sucks) anyone got any idea on how to fix it?

Thanks

Stephen.

James T. Johnson24-Jul-02 16:08

24-Jul-02 16:08

Stephen Woolhead wrote:
Is this normal namespace behaviour?

Yep. Perhaps Eric can explain it better (I just spent 10 minutes trying to and couldn't get it out right) but IIRC namespaces are evaluated from right to left, so the System matches before it gets to the root System namespace; however Diagnostics doesn't match until it gets to the root System namespace.

James
"Java is free - and worth every penny." - Christian Graus

stephen woolhead24-Jul-02 22:13

stephen woolhead

24-Jul-02 22:13

Just seemed strange to me that as I was in the namespace MyNameSpace.System and had a using statement for System when I was used System.Diagnostics, that it should resolve to MyNameSpace.System.Diagnostics instead of trying the following

MyNameSpace.System.System.Diagnostics (Current namespace)
System.System.Diagnostics (Using System Statement)
System.Diagnostics (using the global namespace)

Of which the last one would have been resolved.

Is there a way to say that this is the start of the namespace do not append to anything, something like ::System in C++ ?

Thanks

Stephen

James T. Johnson25-Jul-02 0:16

25-Jul-02 0:16

Stephen Woolhead wrote:
Just seemed strange to me

It does to me too; perhaps this will be addressed in the future (so that it tries all the way up instead of stopping at the first failure -- MyNameSpace.System.Diagnostics)

Stephen Woolhead wrote:
Is there a way to say that this is the start of the namespace do not append to anything

Not that I know of, I think something is needed at any rate.

James
"Java is free - and worth every penny." - Christian Graus

Problems with ListView and columns

jparsons25-Jul-02 2:49

jparsons

25-Jul-02 2:49

Stephen Woolhead wrote:
Is there a way to say that this is the start of the namespace do not append to anything, something like ::System in C++ ?

No but you can try this code example. It's an almost solution to the problem.

using System;
using WinSystem=System;

namespace Test.System { 

	public class Test {
		public static void Main(String[] args) { 
			WinSystem.Console.WriteLine("Hello World");
		}
	}
}

Jared
jparsons@jparsons.org
www.prism.gatech.edu/~gte477n

Luis Alonso Ramos24-Jul-02 9:53

24-Jul-02 9:53

Hi everybody!

I have the following code in the constructor:

        lstUsers = new ListView();<br />
        lstUsers.Parent = this;<br />
        lstUsers.Location = new Point(0, panelTitle.Height);<br />
        lstUsers.Size = new Size(Width, Height - lstUsers.Location.Y + 1);<br />
        lstUsers.Anchor = AnchorStyles.Left | AnchorStyles.Top |<br />
            AnchorStyles.Right | AnchorStyles.Bottom;<br />
        lstUsers.View = View.Details;<br />
<br />
        lstUsers.Columns.Add("Clave",    150, HorizontalAlignment.Left);<br />
        lstUsers.Columns.Add("Nombre",   250, HorizontalAlignment.Left);<br />
        lstUsers.Columns.Add("Permisos", 100, HorizontalAlignment.Right);<br />

The list view appears ok, and when I add items, I can see them in large icon mode (if I remove the View = Details), but in Details mode I don't see anything... not even the column headers (after adding the columns I verified and Columns.Items.Count is indeed 3)

Any ideas???

-- LuisR

──────────────
  Luis Alonso Ramos
  Chihuahua, Mexico
  www.luisalonsoramos.com

"Do not worry about your difficulties in mathematics, I assure you that mine are greater." -- Albert Einstein

leppie24-Jul-02 20:44

leppie

24-Jul-02 20:44

Hi, try adding

listUsers.HeaderStyle = System.Windows.Forms.ColumnHeaderStyle.Nonclickable;

or Clickable.

Hope this helps Smile | :)

MYrc : A .NET IRC client with C# Plugin Capabilities. See
http://sourceforge.net/projects/myrc for more info. Big Grin | :-D

Luis Alonso Ramos24-Jul-02 21:01

24-Jul-02 21:01

Sorry, it didn't work Frown | :(

The only one that seemed to have an effect was ColumnHeaderStyle.None, which removed the place where columns are supposed to appear.

Thanks anyway,

-- LuisR

──────────────
  Luis Alonso Ramos
  Chihuahua, Mexico
  www.luisalonsoramos.com

"Do not worry about your difficulties in mathematics, I assure you that mine are greater." -- Albert Einstein

leppie25-Jul-02 3:28

leppie

25-Jul-02 3:28

Luis Alonso Ramos wrote:
The list view appears ok, and when I add items, I can see them in large icon mode (if I remove the View = Details), but in Details mode I don't see anything...

How are u adding the ListViewItems? If u want to see "multi-columns" make sure it looks like this.

listUser.Items.Add( new ListViewItem( new string[] {"col1itemtext","col2itemtext","col3itemtext"}));
and NOT:
listUser.Items.Add( "colitemtext")

Are u not maybe overwriting the columnheaders?

Hope this helps Smile | :)

MYrc : A .NET IRC client with C# Plugin Capabilities. See
http://sourceforge.net/projects/myrc for more info. Big Grin | :-D

Luis Alonso Ramos25-Jul-02 6:49

25-Jul-02 6:49

Hello,

<br />
while(oReader.Read())<br />
{<br />
    ListViewItem lvi = new ListViewItem();<br />
<br />
    lvi.Text = (string) oReader.GetValue(oReader.GetOrdinal("LoginName"));<br />
    lvi.SubItems.Add((string) oReader.GetValue(oReader.GetOrdinal("Name")));<br />
    lvi.Tag = (int) oReader.GetValue(oReader.GetOrdinal("ID_user"));<br />
<br />
    lstUsers.Items.Add(lvi);<br />
}<br />

This is what I'm using... If I set another view (View.List) for example, the items show OK. It's just the details view that I'm having trouble with.

-- LuisR

──────────────
  Luis Alonso Ramos
  Chihuahua, Mexico
  www.luisalonsoramos.com

"Do not worry about your difficulties in mathematics, I assure you that mine are greater." -- Albert Einstein

leppie25-Jul-02 7:29

leppie

25-Jul-02 7:29

Hehe, from what i can see u dont seem to have VS.NET. In the collection editor u can see (and i had a problem here at 1st too Smile | :)

) how the displayed data is laid out. The ListViewItem is also the 1st SubItem. Try this (i asumme an OleDbReader??)

string[] str_arr = new string[3];
str_arr[0] = (string) oReader.GetValue(oReader.GetOrdinal("LoginName"));
str_arr[1] = (string) oReader.GetValue(oReader.GetOrdinal("Name"));
str_arr[2] = oReader.GetValue(oReader.GetOrdinal("ID_user")).ToString();

lstUsers.Items.Add(new ListViewItem( str_arr));

This is a bit tedious though. I would normally create a LVI property on a class needed to be displayed in detail. Then all i do is use the following constructor for my ListViewItem (from MSDN):

Initializes a new instance of the ListViewItem class with an array of strings representing subitems.

public ListViewItem(string[]);

Hope this gets you going Smile | :)

MYrc : A .NET IRC client with C# Plugin Capabilities. See
http://sourceforge.net/projects/myrc for more info. Big Grin | :-D

Luis Alonso Ramos25-Jul-02 11:04

Re: Problems with ListView and columns (finally fixed)

25-Jul-02 11:04

leppie wrote:
from what i can see u dont seem to have VS.NET

Yes, I'm using Visual C# .NET. But I'm typing most code manually.

The problem is not adding the items, those are added correctly (I can see them as expected in other Views). What I'm having trouble with is adding the columns. In another form I use a list view also and everything works OK. I copied that exact same code to this panel (it's a Panel control, but the one that works is on a TabPage which is also a Panel) and same problem, no columns show up.

I'll give it a try to your way of adding items, but I don't think that will solve it.

Thanks!

-- LuisR

──────────────
  Luis Alonso Ramos
  Chihuahua, Mexico
  www.luisalonsoramos.com

"Do not worry about your difficulties in mathematics, I assure you that mine are greater." -- Albert Einstein

Luis Alonso Ramos12-Aug-02 19:36