Re: How to create a property to get a list on which it'd be impossible to add, replace or remove items ? - C# Discussion Boards

Member 50926227-Aug-03 10:47

27-Aug-03 10:47

from what i understand the app.exe.config file is readonly. if this is true then i can't use it.

Rob

--
There are 10 kinds of people. Those who understand binary and those who don't.

Re: store users settings

Nick Parker27-Aug-03 6:03

Nick Parker

27-Aug-03 6:03

Many people seem to have differing views on this subject, however I have written what I think is a handy class for doing something like this, check my following article: An extension for a Configuration Settings class in .NET[^]

-Nick Parker

Re: store users settings

Frank Olorin Rizzi28-Aug-03 1:37

Frank Olorin Rizzi

28-Aug-03 1:37

This may sound like self-advertising,
but I published something similar
that may (or may not) fit our friend's needs:

http://www.codeproject.com/csharp/CFGLitepack.asp

So, now.. if he wants to use XML, he has Nick's class;
else, he can use mine Smile | :)

Ain't CP great?

F.O.R.

How to create a property to get a list on which it'd be impossible to add, replace or remove items ?

Eric Marchesin26-Aug-03 21:25

Eric Marchesin

26-Aug-03 21:25

Simply, I'd like to create a get property that would return a list of objects for a class, but I want that the list only allows access to items : adding, replacing or removing items must be impossible.

To do that I first wrote the following code :

class MyClass
{
	private ArrayList _AL;
	
	ICollection MyList
	{
		get { return _AL; }
	}
}

Indeed, the ICollection doesn't have Add, Replace or Remove methods.
But I realized later that the ICollection interface returned by MyList could be cast into an IList interface on which it is possible to perform such operations, and then the list can be modified : the data can be acted an unexcepted way, and there is no integrity ! Confused | :confused:

Does anyone know the answer to this architecture problem ?
Regards,

- Éric -

Re: How to create a property to get a list on which it'd be impossible to add, replace or remove items ?

Kannan Kalyanaraman27-Aug-03 1:21

Kannan Kalyanaraman

27-Aug-03 1:21

Did you try making the arraylist

readonly

Regards,
Kannan

Re: How to create a property to get a list on which it'd be impossible to add, replace or remove items ?

Eric Marchesin27-Aug-03 2:02

Eric Marchesin

27-Aug-03 2:02

Unfortunalely that's not the solution.
Indeed readonly attribute will only forbid to replace the ArrayList object AL by another instance, but one can still do anything with the list. For instance, the following code shows that an item can be added normally : it compiles and no exception is thrown.

public class MyClass
{
	public readonly ArrayList AL = new ArrayList();
}

public class MainClass
{
	static void Main()
	{
		MyClass MC = new MyClass();
		try
		{
			MC.AL.Add("toto");
		}
		catch(Exception e) { MessageBox.Show(e.Message); }
		
		foreach ( object O in MC.AL )
			MessageBox.Show(O.ToString()+" has been added !");
	}
}

What a pity... Sigh | :sigh:

- Éric -

Re: How to create a property to get a list on which it'd be impossible to add, replace or remove items ?

leppie27-Aug-03 10:30

leppie

27-Aug-03 10:30

ArrayList.ReadOnly(IList list);

returns a readonly wrapper of your arraylist.

leppie ::AllocCPArticle("Zee blog");

Re: How to create a property to get a list on which it'd be impossible to add, replace or remove items ?

Eric Marchesin27-Aug-03 23:54

Eric Marchesin

27-Aug-03 23:54

Perfect ! That seems to be a good solution.
This static method returns a readonly copy of the ArrayList. Moreover if the original list is modified (directly or through a binding process), then the readonly copy is updated (synchronized). Very well !

Thanks very much.

- Éric -

Re: How to create a property to get a list on which it'd be impossible to add, replace or remove items ?

leppie28-Aug-03 6:58

leppie

28-Aug-03 6:58

Eric Marchesin wrote:
Thanks very much.

Smile | :)

No problem.

leppie ::AllocCPArticle("Zee blog");

Re: How to create a property to get a list on which it'd be impossible to add, replace or remove items ?

Meysam Mahfouzi27-Aug-03 1:28

Meysam Mahfouzi

27-Aug-03 1:28

Take a look at this thread:

http://www.codeproject.com/script/comments/forums.asp?msg=585156&forumid=1649&mode=all&userid=46720#xx585156xx[^]

Smile | :)

Don't forget, that's

Persian Gulf

not Arabian gulf!

Re: How to create a property to get a list on which it'd be impossible to add, replace or remove items ?

Eric Marchesin28-Aug-03 1:03

Eric Marchesin

28-Aug-03 1:03

Finally I'm going to use the following method :

public class MyClass
{
	ArrayList _AL = new ArrayList();
	
	public IList MyList
	{
		get { return ArrayList.ReadOnly(_AL); }
	}
	...
}

- Éric -

Re: How to create a property to get a list on which it'd be impossible to add, replace or remove items ?

Alvaro Mendez27-Aug-03 9:31

Alvaro Mendez

27-Aug-03 9:31

I think there's not much you can do. If you're trying to achieve the same effect as const in C++, the news is that in C++ you can just as easily cast away constness and have the same issue.

Here's my viewpoint:

You as the programmer are doing all you can to make your collection readonly. If someone wants to modify it badly enough, they'll have to take the extra step of casting it and in doing so they assume the responsibility of what problems that may cause.

In other words, it's not your problem. There's only so much you can do and spending time worrying about what some hacker may do is not worth it, IMHO.

Regards,
Alvaro

Hey! It compiles! Ship it.

Re: How to create a property to get a list on which it'd be impossible to add, replace or remove items ?

Alvaro Mendez27-Aug-03 10:47

Alvaro Mendez

27-Aug-03 10:47

Having said all that, I just found a ReadOnly method in ArrayList that gives you the extra safety you need.

Regards,
Alvaro

Hey! It compiles! Ship it.

Re: How to create a property to get a list on which it'd be impossible to add, replace or remove items ?

Anonymous27-Aug-03 23:52

Anonymous

27-Aug-03 23:52

C# applect param pass problem

aw1ay26-Aug-03 20:34

aw1ay

26-Aug-03 20:34

I insert an object(object is writed as winform user control whin c#) in a webform
I want to pass some param to the object
I define the object like this
<object id="AnimTool" height="1024" width="768"
classid="/Web_1/AnimInkControl.dll#SketchBoard.Web.Animation.AnimInkControl"
="" viewastext=""> <param name="Path" />

now I want to pass the param to the object with the user selected path
because the param value is depends on the user selection
so How can I pass the Param to the object?
I used js like this
AnimTool.Path = " df"

but when I open it ,it reports js cann't found the AnimTool object
AnimTool is not define.
why,how?

GPRS communication - PocketPC-SmartPhone..

ZippyBubbleHead26-Aug-03 20:14

ZippyBubbleHead

26-Aug-03 20:14

Hi!
I have a smart phone device based on GSM/GPRS. I used the VS extension ...Smart Devices Extension to
build an application (the GUI and all) for the phone. But now I need to talk to another device which is also GPRS based.

I want a minimal functionality of passing strings from my device to the other.

How do I do this? Could you tell me where I can find information on this topic?

Zippy

help option...

Member 52474026-Aug-03 20:05

Member 524740

26-Aug-03 20:05

i want to provide help in my project..how can i create help? is there any component available..?

-bhavin

Re: help option...

Kannan Kalyanaraman27-Aug-03 23:19

Kannan Kalyanaraman

27-Aug-03 23:19

Search for "Help Provider component" in msdn for more information.
You need to use the HelpProvider class.
To create help you can use tools like robohelp or the html help toolkit or vs help integeration kit[^]

- Kannan

checking items in a ListView

Member 50926226-Aug-03 20:02

Member 509262

26-Aug-03 20:02

i'm having a problem when i check some items in a listview. i have a textbox and a listview and when i check the items in the listview it updates the text in the textbox. my problem is when i check the items my event is always one step behind. example, i check 'a' and nothing happens, i check 'b' and the textbox show 'a', i check 'c' and the textbox shows 'a, b'. what event do i put my code into or is there a trick to this.

thanks,
Rob

my event:

private void lvNameDisplay_ItemCheck(object sender, System.Windows.Forms.ItemCheckEventArgs e)<br />
{<br />
    //<br />
    System.Text.StringBuilder newText = new System.Text.StringBuilder();<br />
    foreach (ListViewItem lvItem in lvNameDisplay.CheckedItems)<br />
    {<br />
        //<br />
        newText.Append(lvItem.Text + ", ");<br />
    }<br />
    tbExample.Text = newText.ToString();<br />
    if (tbExample.Text.EndsWith(", "))<br />
    {<br />
        tbExample.Text = tbExample.Text.Substring(0, tbExample.Text.Length-2);<br />
    }<br />
}

--
There are 10 kinds of people. Those who understand binary and those who don't.

Re: checking items in a ListView

ZippyBubbleHead26-Aug-03 20:38

ZippyBubbleHead

26-Aug-03 20:38

Try writing ur code in the handler for SelectedValueChanged event.
The ItemCheck event is triggered just BEFORE an item is about to be checked...and the value is updated only AFTER this event completes...that explains the "lag" u xperienced!

private void listview_SelectedValueChanged(object sender, System.EventArgs e)
{

System.Text.StringBuilder newText = new System.Text.StringBuilder();
System.Windows.Forms.CheckedListBox.CheckedItemCollection col = clv.CheckedItems;

foreach (Object obj in col)
{
//
newText.Append(obj.ToString() + ", ");
}
t1.Text = newText.ToString();
if (t1.Text.EndsWith(", "))
{
t1.Text = t1.Text.Substring(0, t1.Text.Length-2);
}
}

Zippy

Re: checking items in a ListView

Member 50926226-Aug-03 21:55

Member 509262

26-Aug-03 21:55

thank you for the help but i'm using a listView not a listBox. the listView doesn't have an event for selectedvaluechanged.

thanks,
Rob

--
There are 10 kinds of people. Those who understand binary and those who don't.

#include "wincrypt"

devvvy26-Aug-03 19:06

devvvy

26-Aug-03 19:06

trying to use CAPI, so I included the header on top of my WIN32 console app:

#include "stdafx.h"

#using <mscorlib.dll>
#include <tchar.h>

#include "wincrypt.h" <--- remove this, all problems are gone?

using namespace System;

// This is the entry point for this application
int _tmain(void)
{

return 0;
}
C:\Program Files\Microsoft Visual Studio .NET\Vc7\PlatformSDK\Include\WinCrypt.h(37): error C2146: syntax error : missing ';' before identifier 'HRESULT'

The error trace to this line here:
#ifndef _HRESULT_DEFINED
#define _HRESULT_DEFINED
typedef LONG HRESULT; <-- THIS LINE

Any idea?

norm

Re: #include "wincrypt"

David Stone26-Aug-03 19:40

David Stone

26-Aug-03 19:40

This here is the C# forum, you want to go to the C++ forum. Smile | :)

Norm Almond:I seen some GUI's in my life but WTF is this mess
Leppie:I made an app for my sister and she wouldnt use it till it was colorful enough
Norm:good point leppie, from that statement I can only deduce that this GUI must be aimed at children
Leppie:My sister is 25
-Norm on the MailMagic GUI

Re: #include "wincrypt"

devvvy26-Aug-03 19:54

devvvy

26-Aug-03 19:54

But, i already figured it out. Smart arses from MSDNS omitted:

#define _WIN32_WINNT 0x0400
#include <windows.h>
#include <wincrypt.h>
#define MY_ENCODING_TYPE (PKCS_7_ASN_ENCODING | X509_ASN_ENCODING)

man, just can't stop picking on MSDN people - perhaps I sufferred too much in my distant past doing MFC. Must say, reading their doc isn't the most efficient thing i do.

norm

Getting an intersect of a color

Ista26-Aug-03 16:01

Ista

26-Aug-03 16:01

I need to get the intersection of Green and Yellow in ARGB format

Is there a function for this.

And yes I know Color.GreenYellow exists but I need to know how to get intersections to achieve other mid way points.

nick

I'm not an expert yet, but I play one at work. Yeah and here too.

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