Re: sealed classes - C# Discussion Boards

Re: String.IsNullOrEmpty

Colin Angus Mackay6-Sep-07 1:13

Colin Angus Mackay

6-Sep-07 1:13

Seriously, for the additional fractions of a microsecond that IsNullOrEmpty takes I wouldn't worry about it.

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Re: String.IsNullOrEmpty

PIEBALDconsult6-Sep-07 4:47

PIEBALDconsult

6-Sep-07 4:47

Won't .Length check for null again anyway? If so, you're checking for null twice.

I'd just use IsNullOrEmpty figuring Microsoft wouldn't steer me wrong. Big Grin | :-D

Re: String.IsNullOrEmpty

Colin Angus Mackay6-Sep-07 6:00

Colin Angus Mackay

6-Sep-07 6:00

PIEBALDconsult wrote:
Won't .Length check for null again anyway? If so, you're checking for null twice.

.Length cannot operate on null so it will throw an exception.

Re: String.IsNullOrEmpty

PIEBALDconsult6-Sep-07 6:24

PIEBALDconsult

6-Sep-07 6:24

::Smacking forehead with heel of hand::

sealed classes

Sonia Gupta5-Sep-07 23:29

Sonia Gupta

5-Sep-07 23:29

i know the meaning of sealed classes.My Question is when should i use the sealed classes.

Sonia Gupta
Soniagupta1@yahoo.co.in
Yahoo messengerId-soniagupta1
Love is Friendship and Friendship is Love....

Re: sealed classes

originSH5-Sep-07 23:46

originSH

5-Sep-07 23:46

Well the meaning of it shows when it should be used ... it stops anyone inheriting your class, so it should be used when you don't want someone to inherit your class :P

Two examples of this in the Base Class Libraries are the List and String Builder. These 2 are sealed as they are "high performance" classes which microsoft don't want anyone inheriting and then messing around with the internals and messing them up (well thats the official line anyway).

Re: sealed classes

Sonia Gupta6-Sep-07 0:52

Sonia Gupta

6-Sep-07 0:52

I KNOW IT SHOULD BE USED TO DEPRIVE OF SOME INHERITING MY CLASSES.
BUT ONE CAN ACCESS THE MEMBER FUNCTIONS AND MEMBER VARIABLES BY INSTANTIATING THE CLASS.

Sonia Gupta
Soniagupta1@yahoo.co.in
Yahoo messengerId-soniagupta1
Love is Friendship and Friendship is Love....

Re: sealed classes

Urs Enzler6-Sep-07 1:05

Urs Enzler

6-Sep-07 1:05

Sure, you can access the members of a sealed class. sealed is not an access modifier like private, protected, public, internal, protected internal.

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Re: sealed classes

Pete O'Hanlon6-Sep-07 1:35

Pete O'Hanlon

6-Sep-07 1:35

Please - no shouting. Your keyboard has both upper and lower case.

Deja View - the feeling that you've seen this post before.

Re: sealed classes

Pete O'Hanlon6-Sep-07 1:49

Pete O'Hanlon

6-Sep-07 1:49

Yes. And your point was?

Sealed doesn't mean it can't be instantiated - that's what abstract means. It just means that it can't be inherited.

Deja View - the feeling that you've seen this post before.

Re: sealed classes

PIEBALDconsult6-Sep-07 4:49

PIEBALDconsult

6-Sep-07 4:49

Hardly ever; it's rude. I very much dislike running up against sealed classes and having to find a less-elegant solution than inheritance.

Re: sealed classes

Scott Dorman6-Sep-07 18:09

Scott Dorman

6-Sep-07 18:09

PIEBALDconsult wrote:
I very much dislike running up against sealed classes and having to find a less-elegant solution than inheritance.

I agree on this point, but there are also cases where sealed classes are useful. The most common use are for performance sensitive classes, utility helper classes (which can now use the static keyword, which also makes them sealed), and value types (all enums are sealed).

With the upcoming .NET 3.5 release, not being able to inherit a sealed class becomes less of an issue due to extension methods.

Scott.

—In just two days, tomorrow will be yesterday.

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Insert character

M Riaz Bashir5-Sep-07 23:14

M Riaz Bashir

5-Sep-07 23:14

Hi,

Kindly help me that, How can I insert a character between any string value?
Example: string value is : ABC/DEF/GHI
after inserting..........: ABC-DEF-GHI

Thank you in advance

Re: Insert character

blackjack21505-Sep-07 23:22

blackjack2150

5-Sep-07 23:22

Use the Insert method of the string class.
However, in your example you replaced a character with another one. In this case use the Replace method.

Re: Insert character

Revathij5-Sep-07 23:53

Revathij

5-Sep-07 23:53

use Replace function
for example : string str="ABC/DEF/GHI";
str=str.replace('/','-')

Post-Build on Vista

Russell Jones5-Sep-07 23:04

Russell Jones

5-Sep-07 23:04

When my post build event runs I get this message

Error 1 The command "copy bin\Debug\plugin.dll C:\Program Files\SomeApp\Plugins" exited with code 1.

If i open an elevated commandline at the project folder I can execute the command perfectly well.

I'm running VS2005 as admin and i need to copy my plugin to the apps plugins folder inorder to run it. This isn't my app, it's an app I'm integrating with so I can't change the location of the plug-ins folder.

Any Ideas?

Thanks

Russell

Re: Post-Build on Vista

mav.northwind6-Sep-07 0:37

mav.northwind

6-Sep-07 0:37

Doesn't really have to do anything with C#, does it?
Anyway, you should start reading about UAC under Vista. You'll learn (among other things) that even running an application while logged in as admin won't give you the same access rights XP gave you.
You could try running VS with elevated rights or turn off UAC completely.

Regards,
mav

--
Black holes are the places where God divided by 0...

Re: Post-Build on Vista

Russell Jones6-Sep-07 3:33

Russell Jones

6-Sep-07 3:33

i guess it's got very little to do with c#, it would probably be better in the Vista forum but i thought it was a problem that other c# developers might be running up against so i posted it here.

I am running the VS IDE as Administrator rather than running it when logged in as administrator. I've been fighting battles with UAC for a while now and I thought I had a handle on it but this seems really confusing, i'm not even 100% sure if it is an issue with UAC.

Russell

A question in Implement COM interface in C# [modified]

G.Richard5-Sep-07 22:52

G.Richard

5-Sep-07 22:52

Experts,

I want to implement some COM interfaces in C#, and these interface will be called by a DLL written by ATL. The COM interface definations are :

__interface IDataRelation : IUnknown
{
...
HRESULT GetData(
[in] long Item,
[in] REFIID riid,
[out, iid_is(riid), retval] void **Data);
}

__interface IArray : IUnknown
{
...
}

__interface INumber : IArray
{
....
HRESULT GetUnits([out, retval] BSTR *Units);
}

__interface IDoubleNumber : INumber
{
...
}

The native code will call IDataRelation.GetData() to get the pointer of INumber to get the data unit.

I rewrite the interfaces in C#

[ComImport, Guid(XXX), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface IArray {...}

[ComImport, Guid(XXX), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface INumber : IArray
{
...
[Return : MarshalAs(UnmanagedType.BSTR)]
string GetUnit();
}

[ComImport, Guid(XXX), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface IDoubleNumber : INumber {...}

[ComImport, Guid(XXX), InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
public interface IDataRelation
{
[Return : MarshalAs(UnmanagedType.Interface)]
object GetData(
[In, MarshalAs(UnmanagedType.I4)]
int Item,
[In, MarshalAs(UnmanagedType.Struct)]
ref Guid riid);

}

Then I construct two classes to implement these interfaces.

public class ArrayBase : IArray, INumber, IDoubleNumber
{
string INumber.GetUnit()
{
return m_Unit;
}
}

public class Data : ArrayBase, IDataRelatin
{
...
public object GetData(int Item, ref Guid riid);
{
return this;
}
}

Every thing seems fine, IDataRelation can be retrived in the C++ code.

CComQIPtr<idatarelation> pRelation = GetDataRelation(...); //Get data relation

if(pRelation != NULL)
{
CComQIPtr<inumber> testNumber;
pRelation->GetData(0, UUIDOF(INumber), reinterpret_cast<void**>( &testNumber ));
if(testNumber != NULL)
{
CComBSTR m_DataUnit;
testNumber->GetUnit(&m_DataUnit); //Error !!!
}
}

When I call GetUnit, a strange error occured, see the following detail :

Run-Time Check Failure #0 - The value of ESP was not properly saved across a function call. This is usually a result of calling a function declared with one calling convention with a function pointer declared with a different calling convention.

The ATL DLL is used to display a chart. I use it in my C# project. The above interfaces are its

data source interface. I just want to implement these interfaces to supply my own data source for

it. My project is not a COM server and not COM visible.

The ATL DLL is written years ago, but only used by other C++ projects and have no problem, I can't change anything.

I haved searched for the above error solution, but got nothing.

Now, Any idea?

-- modified at 5:01 Thursday 6th September, 2007

c++ : my dream

RichTextBox keyboard cursor

mihksoft5-Sep-07 22:25

mihksoft

5-Sep-07 22:25

Hy
Can anybody tell me how can I set the position of the keyboard (not mouse) cursor in a RichTextBox.

thanks

Re: RichTextBox keyboard cursor

mav.northwind6-Sep-07 0:30

mav.northwind

6-Sep-07 0:30

Hi!
A quick glance at the basic documentation of the RichTextBox will tell you that the SelectionStart and SelectionLength property or the Select() method will achieve this.
That's what documentation is there for... Roll eyes | :rolleyes:

Regards,
mav

--
Black holes are the places where God divided by 0...

Modal Windows in smart parts

umashankergr85-Sep-07 21:29

umashankergr8

5-Sep-07 21:29

Hi All,

Will anyone help in opening a View which is having its own Interface and Presenter. I want to open this view from base presenter in ModalWindow style. the code which i am having throws error "Object reference not set to an instance" in this line of code "WorkItem.Workspaces[WorkspaceNames.ModalWindows].Show(ObjMailLeft);". I need a sample application so that i can understand better..

Thanks in advance

Umashanker.K

OLEDB problem

sulabh20205-Sep-07 21:28

sulabh2020

5-Sep-07 21:28

Hi coder,
I am facing an problem with my application, which is using As access database as an back end.
when i am running the application after istalling to system it throws an exception of OLEDB 4.0 not registered on your local system

Please suggest me what to do.

If i need to istall the driver than plz if possible give me link for the same

Thanks in advance.

Hello Forum
Always be in touch to help about the topic ASP.NET

Re: OLEDB problem

Pete O'Hanlon5-Sep-07 21:39

Pete O'Hanlon

5-Sep-07 21:39

Googling this problem brought lots[^] of results. Why didn't you try it first?

With a couple of clicks I found this[^]. Seriously, if you want to become a professional problem you will have to learn how to solve problems like this yourself.

Deja View - the feeling that you've seen this post before.

Re: OLEDB problem

sulabh20205-Sep-07 21:42

sulabh2020

5-Sep-07 21:42

Hi thanks fo rthe reply.

I have alresdy googled lot but failed to resolve.
i also installed latest service pack for the OS but again facing prob.

Hello Forum
Always be in touch to help about the topic ASP.NET

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