Re: Application Global Properties - C# Discussion Boards

18-Apr-04 1:42

Hello:

Is there a way to set application properties that are global and accessible from all points in the program. I have tried public static classes, constants, properties on the main form, properties in the app object, but it always tells me that the "prop" is not in scope.

How do you guys handle this kind of problem for setting application wide defaults. It was easy in vfp, but i'm pulling my hair out here (what's left of it anyway).

Thanks.

CWIZO18-Apr-04 1:53

18-Apr-04 1:53

Having one class with static fields is good. Just make shure that all class'es are in the same namespace.

Q:What does the derived class in C# tell to it's parent?
A:All your base are belong to us!

John Baird18-Apr-04 1:56

18-Apr-04 1:56

The classes are in different namespaces. I thought adding a reference to the individual namespaces would allow me access to the class from anywhere. Is that not true?

CWIZO18-Apr-04 2:12

18-Apr-04 2:12

By adding refrence you mean:

using YourNameSpace; ?

the using statment is only aplied to one file if it is placed outside the namespace {} block!

Q:What does the derived class in C# tell to it's parent?
A:All your base are belong to us!

John Baird18-Apr-04 2:31

18-Apr-04 2:31

Thanks for replying, but I'm still lost. I'm trying to load the values into a static structure now. The values are loaded, but when I try to access them from the watchwindow, I get the "out of score" error.

Pardon me, but here is the code. Can you tell me what's wrong?

<font size = 1>using System;
using System;
using AMS.Profile;


namespace MySpace
{
	/// <summary>
	/// Summary description for AppStartUp.
	/// </summary>
	public class AppStartUp
	{
		public AppStartUp()
		{
			//
			// TODO: Add constructor logic here
			//
		}

		public struct AppDefaults
		{
			public static string server = "";
			public static string dataBase = "";
			
			public static string adminPath = "c:\vsdevelop";
			public static string sqlConn = "";		
		}

		public static void SetAppDefaults()
		{
			Registry profile = new Registry();
			AppDefaults.server = profile.GetValue("DBSettings","DBServer","");
			AppDefaults.dataBase = profile.GetValue("DBSettings","DBName","");
			
			AppDefaults.adminPath = "c:\vsdevelop";
			AppDefaults.sqlConn = "SERVER=" + AppDefaults.server.ToUpper().Trim() + ";UID=uid; PWD=pwd;DATABASE=database";
		}
		
		public static void LoadProgramSettings()
		{
			SetAppDefaults();
			
		}
	}
}

</code>

CWIZO18-Apr-04 3:51

18-Apr-04 3:51

You are trying to set a value to a field that is inside the structure, onyl specifying the class ...
And even so I think you must declare the structure as static too ...

but I really don't know why you are using a structure in the above code (dump it)...

Q:What does the derived class in C# tell to it's parent?
A:All your base are belong to us!

John Baird18-Apr-04 3:55

18-Apr-04 3:55

Thanks for your help. I've finally been able to get it to work.

Dump it in favor of what? classes.

There has been some discussion on speed using structures for static storage. It seems that most favor the structure. You reasons?

CWIZO18-Apr-04 4:32

18-Apr-04 4:32

It has no sense in using a structure like that.
There is no need for you to "group" fields inside a structure, becouse you already have them inside your class.

Maybe you should read some article that covers the OO aproach to desigening programms Smile | :)

Q:What does the derived class in C# tell to it's parent?
A:All your base are belong to us!

Heath Stewart19-Apr-04 2:35

19-Apr-04 2:35

To add, you may want to consider caching the settings instead of reading them from the registry each time. If they can be changed throughout your application, then have additional methods on this class that can reset some flag so that the values would be read and cached again.

Also, use a private constructor so that callers can't instantiate this class since that would serve no purpose. In .NET 2.0, you don't need to do this if you use static classes (prefix your class declaration with static). This will be out early next year, just FYI.

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Anonymous19-Apr-04 2:52

Anonymous

19-Apr-04 2:52

Hello:

Thanks for responding. I'm loading the values into the global properties one time at application startup. In that instance, would caching the values give me any benefit?

Heath Stewart19-Apr-04 3:12

what should I do? marhal or unsafe???

19-Apr-04 3:12

Well first, you need to expose them. You're simply setting them on a struct, which goes out of scope so they can never be read again. While I don't particularly find this approach to settings at all attractive from an OO standpoint, the least you can do is provide static properties on this class using the guidelines I outlined. What you're doing right now won't work at all because the struct simply goes out of scope like in the rest of your thread the other replier mentioned.

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Paolo Ponzano18-Apr-04 0:51

18-Apr-04 0:51

Hi, I think in a near time you'll hate me, I'm porting code from C to C#, I've this structure define in unrar.h

<br />
struct RAROpenArchiveDataEx<br />
{<br />
  char         *ArcName;<br />
  wchar_t      *ArcNameW;<br />
  unsigned int OpenMode;<br />
  unsigned int OpenResult;<br />
  char         *CmtBuf;<br />
  unsigned int CmtBufSize;<br />
  unsigned int CmtSize;<br />
  unsigned int CmtState;<br />
  unsigned int Flags;<br />
  unsigned int Reserved[32];<br />
};<br />

and should be used by unrar.dll's function
HANDLE PASCAL RAROpenArchiveEx(struct RAROpenArchiveDataEx *ArchiveData);

I tryied using mashalling to mirror dll's structure in C#, but invoking RAROpenArchiveEx it hangs up, supposing due to the pointer to ArchiveData....

How should I go on? I don't know how to convert

unsigned int Reserved[32];
wchar_t *ArcNameW;

thanks....

Daniel Turini18-Apr-04 1:14

Daniel Turini

18-Apr-04 1:14

Paolo Ponzano wrote:
Hi, I think in a near time you'll hate me, I'm porting code from C to C#, I've this structure define in unrar.h
I think in a near time you'll hate me, but why aren't you using managed C++? Simply write a bunch of wrapper classes, compile with /CLR, and you're done!

Due to technical difficulties my previous signature, "I see dump people" will be off until further notice. Too many people were thinking I was talking about them...

Paolo Ponzano18-Apr-04 1:30

18-Apr-04 1:30

I don't know...... I started with C# and since I also have applied a lot of improvement I don't want to redo all again =)
May I only do the unpacking routine in C++ managed and all the rest in C#?

leppie18-Apr-04 4:50

leppie

18-Apr-04 4:50

Thats the idea Smile | :)

^{top secret AdvancedTextBox}

Paolo Ponzano18-Apr-04 8:37

18-Apr-04 8:37

but have I to create a new project and write a dll that will be invoked? or what? can I use C++ code in a C# project? I don't think so.....and I don't also how to let C# to use C++ code...thanks again

Paolo

Heath Stewart19-Apr-04 2:42

19-Apr-04 2:42

It should look something like this:

[StructLayout(LayoutKind.Sequential)]
public struct RAROpenArchiveDataEx
{
  [MarshalAs(UnmanagedType.LPStr)] string ArcName;
  [MarshalAs(UnmanagedType.LPWStr)] string ArcNameW;
  [MarshalAs(UnmanagedType.U4)] int OpenMode;
  [MarshalAs(UnmanagedType.U4)] int OpenResult;
  [MarshalAs(UnmanagedType.LPStr)] string CmtBuf;
  [MarshalAs(UnmanagedType.U4)] int CmtBufSize;
  [MarshalAs(UnmanagedType.U4)] int CmtSize;
  [MarshalAs(UnmanagedType.U4)] int CmtState;
  [MarshalAs(UnmanagedType.U4)] int Flags;
  [MarshalAs(UnmanagedType.ByValArray, SizeConst=32)] int[] Reserved;
}
[DllImport("rar32.dll")] // Or whatever library in which the func's defined
private static extern IntPtr RAROpenArchiveEx(ref RAROpenArchiveDataEx data);

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Paolo Ponzano19-Apr-04 7:43

19-Apr-04 7:43

thanks a lot... but how I declare in my method the structure??

this way -> RarOpenArchiveDataEx data = new RarOpenArchiveDataEx()???

or since in dll's function RAROpenArchiveEx I've a ref to that structure I need to use something I don't know?

thanks again

Paolo

Heath Stewart19-Apr-04 8:45

19-Apr-04 8:45

Create an instance of your struct and pass it to your method:

RAROpenArchiveDataEx data = new RAROpenArchiveDataEx();
// ... assign values to fields if necessary
IntPtr retVal = RAROpenArchiveEx(ref data);
// Get values from fields from the data variable, now.

Microsoft MVP, Visual C#
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Paolo Ponzano19-Apr-04 9:14