C / C++ / MFC

Smart Pointer implementation question

15-Aug-02 2:00

gm_coll wrote:
Will this not have already generated an exception when the data containing non-numeric characters is attempted to map to my double?

Yes, the exception was already generated and user has seen the MFC's message box. But you wanted to do something extra (at least this is what you originally posted). The catch block in DoDataExchange is your chance - you're getting control before DoDataExchange returns to CWnd::UpdateData.

Tomasz Sowinski -- http://www.shooltz.com

Never argue with an idiot, he'll bring you to his level and beat you with experience.

pankajdaga14-Aug-02 23:50

pankajdaga

14-Aug-02 23:50

Hi,

I have a simple smart pointer implementation. Now, I want the pointer to allow type casting. For example, a derived class should be able to cast back to the base class etc. Any ideas on how to do this?

Here is the implementation so far:

template <class t="">
class SmartPtr
{
public:

/**
Default constructor.
*/
SmartPtr(): _p (0) {}

/**
Pass new directly as the argument
*/
SmartPtr (T* p): _p (p) {}

/**
Copy constructor
*/
SmartPtr(SmartPtr& source) :_p(source.Acquire())
{}

/**
Assignment operator: transfers ownership
*/
SmartPtr& operator= (SmartPtr& pSource)
{
if (_p != pSource._p)
{
delete _p;
_p = pSource.Acquire();
}
}

/**
Delete the pointer, when going out of scope.
The pointer does not get deleted if the owner has changed
*/
~XPtr () { delete _p; }

/**
Null out the pointer. So if the owner has changed and
this object goes out of scope, it does not delete the pointer.
*/
T* Acquire ()
{
T * pTmp = _p;
_p = 0;
return pTmp;
}

/**
for pointer like syntax
*/
T * operator->() { return _p; }

/**
Get the raw pointer
*/
T const & GetAccess () const { return *_p; }

private:
/**
The raw pointer
*/
T * _p;
};

Thanks,

Pankaj

Without struggle, there is no progress

Tomasz Sowinski14-Aug-02 23:59

14-Aug-02 23:59

Add 'operator T* () { return _p; }'

Tomasz Sowinski -- http://www.shooltz.com

Never argue with an idiot, he'll bring you to his level and beat you with experience.

pankajdaga16-Aug-02 1:45

pankajdaga

16-Aug-02 1:45

Thanks! That worked! However, how is it that we do not have to supply any return type? Does C++ automatically determine the return type according to the casting operator. Also, I did not know that a class function could be without a return type. However, it works! So obviously I need to learn a lot! Any input on this will be greatly appreciated!

Pankaj

Without struggle, there is no progress

Stuart Dootson15-Aug-02 11:15

Stuart Dootson

15-Aug-02 11:15

Without wishing to sound nasty or dificult or stupid...is this smart pointer implementation giving you anything more than auto_ptr in the Standard C++ Library - and if not, why not just use that?

Stuart Dootson

'Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p'

pankajdaga16-Aug-02 1:43

pankajdaga

16-Aug-02 1:43

I know I can use auto_ptr. I am not really using it in any project. It just feels good to know that you can implement this behavior sometime. Also, gives me a better understanding of the language and everything. Basically, just for educational purposes. That is all Smile | :)

Pankaj

Without struggle, there is no progress

Something changed in MFC in VC7.0

Stuart Dootson16-Aug-02 9:39

Stuart Dootson

16-Aug-02 9:39

Hey, that's cool - I've often done things to educate myself - experience IS the best way to learn. Just wanted to make sure you weren't implementing it because you didn't know about the already written alternatives!!

Stuart Dootson

'Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p'

Mukkie14-Aug-02 22:53

Mukkie

14-Aug-02 22:53

Hi!

I recently ported several my projects from VC6 to VC7. I have noticed large memory leaks. After some debugging, I have found out that ExitInstance is not called any more. This is due to fact, that window is destroyed far more earlier (I think) than before. Application exits (quits ,immediately) in CFrameWnd::OnClose() during DestroyWindow() - last line in this method.
What is the reason?

I cannot find any document which describes this issue.
Confused | :confused:

is it possible?

shakir14-Aug-02 21:31

shakir

14-Aug-02 21:31

hi!!
anyone can help me?

i want to know that thru consloe program can we pass the values to windows program & can invoke the windows application to display the output.

plz help me
thanks!!

bebe harhour14-Aug-02 22:02

bebe harhour

14-Aug-02 22:02

Yes it depends on the task u want to do, but to launch an application Nishat S has a good article on code project

Anonymous14-Aug-02 23:34

14-Aug-02 23:34

thanks for replying!
but from where can i get this article.
plz tell me.

shakir14-Aug-02 23:34

shakir

14-Aug-02 23:34

thanks for replying!
but from where can i get this article.
plz tell me.

Anonymous16-Aug-02 21:40

Changing the font of Edit Box

16-Aug-02 21:40

http://www.codeproject.com/system/newbiespawn.asp

BindDefaultProperty??

DerBay14-Aug-02 21:10

DerBay

14-Aug-02 21:10

How I can use "BindDefaultProperty" of an editbox
to bind a field of a disconnected recordset.

Shibu14-Aug-02 20:51

Shibu

14-Aug-02 20:51

Hi all,

How can i change the font of Text Box (Edit Box) ?.
With regards

Re: Changing the font of Edit Box

Tomasz Sowinski14-Aug-02 23:22

Bitmap with scrolling capability

14-Aug-02 23:22

Did you try with SetFont?

Tomasz Sowinski -- http://www.shooltz.com

Never argue with an idiot, he'll bring you to his level and beat you with experience.

Shibu14-Aug-02 20:37

Shibu

14-Aug-02 20:37

Hi all,

I have plced a Bitmap in my control in a static frame using the Load Image Function.Now the bitmap is seen as a compressed or expanded one depending on the bitmap selected to load in that frame. How can i make the bitmap to fit in my frame with the full size in such a manner that the visible part of the image is seen on the static frame and the remaining portions are seen when a scroll bar at bottom or side is moved?. In short how can i show a bitmap in a static frame with scrolling using load Image Function?.

With regards

Re: Bitmap with scrolling capability

Tomasz Sowinski14-Aug-02 23:46

Show popup menu not animated?

14-Aug-02 23:46

Shibu wrote:
In short how can i show a bitmap in a static frame with scrolling

You can't. You'll have to create your own window which supports loading images and scrolling.

Tomasz Sowinski -- http://www.shooltz.com

Never argue with an idiot, he'll bring you to his level and beat you with experience.

Attributes and MFC

paulb14-Aug-02 18:52

paulb

14-Aug-02 18:52

I was attempting to use ATL attributes in VS.NET in a MFC project (to hook to an event fired by a COM object) but in order to get it to compile had to include the [module(name="SomeName")] attribute. AFAIK this generates DllMain, DllRegisterServer, and whatnot code, but as an MFC app it already has a WinMain?! Well the app compiles and works, but I am wondering if this is correct or I am doing something wrong?

Dialog windows

Jason Hooper14-Aug-02 18:48

Jason Hooper

14-Aug-02 18:48

I have a small dialog window that is a child of my parent dialog. It has the topmost window style set so I can be doing things in other windows and have my small child window of my app still visible on top of everything. When I click on the title bar to move it around the screen, upon releasing the mouse button, the parent dialog box pops up to right under the child dialog. This isn't the behaviour I'm desiring (I'd like to be able to move the child window around without seeing the parent, but I'm not sure how to get around it, or what to do. Any ideas?

Also, i'm taking a plain dialog resource for it (no controls), and in my OnPaint function for that dialog, calling GetClientRect() and drawing right to that rect. Is this wise?

- Jason
(SonorkID 100.611)

The Code Project - Orange makes the art grow fonder

Re: Dialog windows

DanielO15-Aug-02 0:37

DanielO

15-Aug-02 0:37

hu?

CParentDlg::ShowChild()
{
dialog dlg

ShowWindow(SW_HIDE)

if( dlg.DoModal()== IDOK)
{
//bla bla
}

ShowWindow(SW_SHOW)

-Drawing on that plain dlg that OnPaint (WM_DRAW) message should do no harm

Daniel O

Anonymous14-Aug-02 18:37

Re: Show popup menu not animated?

14-Aug-02 18:37

Can I create a popup menu (context menu) and make it apear at once, no animation.

Can I get the height of the created menu, I'd like to position it exatcly above a button?

Thanks for help!

Roman Fadeyev14-Aug-02 19:20

Roman Fadeyev

14-Aug-02 19:20

1) I think you can't. There is only one way to solve this problem - switch "menu effects" options off in Windows Settings. Of course, you can paint menu manually, but is it worthy of that efforts?

2) Point is that Windows can place popup menus in different directions relative to point that you indicated to menu. It depends on how close this menu is to bounds of screen. If you will adjust menu position manually, it may result a bug in some particular case

Re: Show popup menu not animated?

Anonymous14-Aug-02 19:23