Tree Control Check Boxes... ??? - C / C++ / MFC Discussion Boards

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Re: Advanced Function Pointer?

Aidman7-Jan-03 10:50

Aidman

7-Jan-03 10:50

Please understand that I don't wanto use any already designed scripts, escially an script object. I wanto create my own language and own engine Smile | :)

Aidman » over and out

Function Pointers in OOP

tilli again6-Jan-03 11:11

tilli again

6-Jan-03 11:11

Hey everyone!

Okay, I have the following code:

typedef int (*funcP) (int v1, int v2);

struct pStruc
{
funcP callback;
};

struct pStruc *callbacks;

int someFunc (int v1, int v2)
{
return v1 + v2;
}

int anotherFunc (int v1, int v2)
{
return v1 - v2;
}

struct pStruc *assignFuncs ()
{
return (struct pStruc []) {&someFunc, &anotherFunc};
}

void main ()
{
callbacks = assignFuncs ();
cout << callbacks->callback (10, 20);
}

Output will be 30.

You should get the idea: I have an array of function pointers, and I need to call the stored functions. Works so far. Now, what will I have to do if assignFuncs as well as the two refered functions are members of some class? I'd like to have it working in a very flexible way, without any hardcoded class name! Any idea?

tilli

Re: Function Pointers in OOP

Alvaro Mendez6-Jan-03 11:38

Alvaro Mendez

6-Jan-03 11:38

I'd like to give you an exact answer but I'm afraid my experience with member function pointers is extremely limited (thank God). If you haven't already, you may want to search the C/C++ articles here for ways of accomplishing what you need.

What I'd like to know is why? Why go through this syntactic nightmare when OO techniques such as virtual functions may provide a more elegant and maintainable solution?

Regards,
Alvaro

Well done is better than well said. -- Benjamin Franklin
(I actually prefer medium-well.)

Re: Function Pointers in OOP

William E. Kempf6-Jan-03 12:03

William E. Kempf

6-Jan-03 12:03

C++ is strongly typed, so you can't use member-function pointers with out a class name. Nor can you mix function pointers with member-function pointers. However, you can accomplish what you want (and a lot more) by giving up on function pointers and turning to higher level "function objects" with libraries like Loki or Boost.Function (and Boost.Bind is quite handy when using Boost.Function as well!). http://www.boost.org[^]

William E. Kempf

Re: Function Pointers in OOP

valikac6-Jan-03 16:07

valikac

6-Jan-03 16:07

One solution is static declaration. Given assignFuncs points to a class member function, then that class member function must be static if you want to call it anytime and anywhere. Otherwise, you must call it via object.

Kuphryn

Re: Function Pointers in OOP

tilli again7-Jan-03 8:43

tilli again

7-Jan-03 8:43

Great! Making them static is working. To answer the question about "why the hassle": I'm writing on an Win32 API OOP Wrapper, and I wanted the user to be able to overwrite a function (assignFunc in this case) which is called by the class during the initialization process. What it does then is returning a list of Window Messages with their corresponding callback functions. Once a message needs to be processed then, the window message loop checks if the message has a callback defined and launches it. The reason I wanna be able to use class member functions for this purpose is so the callback functions can use member variables.

tilli

Re: Function Pointers in OOP

tilli again8-Jan-03 8:18

tilli again

8-Jan-03 8:18

Well...making them static did work for what I wanted. But I'm no more able to access non-static functions from these functions then, so the intended advantage over non-class-functions will be exactly void. So, anyone has an idea how to rewrite the original code? I'd like to keep something at least somewhat similiar to the current approach, because I found it to be quite convenient and flexible for the user!

Thanks
tilli

Tree Control Check Boxes... ???

work_to_live6-Jan-03 9:31

work_to_live

6-Jan-03 9:31

I inserted a tree control in a dialog box, and enabled the Check Boxes property. Then I load up the control with items, allow the user (me right now) to select some of them by placing checks next to the items of interest.

All is well and good. The only problem I have is... I can't figure out how to determine which items have been checked! Any help would be greately appreciated.

Thanks,
Gary H

Re: Tree Control Check Boxes... ???

work_to_live6-Jan-03 9:51

work_to_live

6-Jan-03 9:51

I found it...

I was looking at the item state, and didn't realize there was a GetCheck member function of CTreeCtrl. I knew it was going to be simple.

Later.

Synchronization.. do I need?

Subrahmanyam6-Jan-03 9:15

Subrahmanyam

6-Jan-03 9:15

I have a dialog based application in which I have two sources of events
1) On Timer
2) On User input(such as click of button)

Now on both events I will be calling a function, which acts on a single resource.
Calling the function while it is already executing is dangerous & can corrupt all my data.

Now I want to know do I need to put any synchronization code (SingleLock etc.) in my function.

** The important point here is that I am not creating any threads explicitly.
So my assumption is that my app is single threaded. In such case my function can never be called (from anywhere else) while it is running.

Am I correct? Am I missing anything here?

Please help me.

Re: Synchronization.. do I need?

Tim Smith6-Jan-03 10:17

Tim Smith

6-Jan-03 10:17

Since you only have one thread, you need not worry.

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

Re: Synchronization.. do I need?

C^hris L^osinger6-Jan-03 10:59

C^hris L^osinger

6-Jan-03 10:59

you might not need SingleLock, etc.. but if there's a chance you could end up going through the same function twice at the same time (especially if you're doing message pumping) you might need to use a flag at the top of any functions where this could be dangerous.

bool g_alreadyInFuncA = false;

void funcA()
{
  if (g_alreadyInFuncA)
  {
    error? return early? crash?
  }

  g_alreadyInFuncA = true;

  blah 
  blah
  MessagePump...
  blah
  g_alreadyInFuncA = false;
}

void OnMyMessage()
{
 funcA()
}

-c

I'm not the droid you're looking for.

ThumbNailer

Debugging Mutexes?

clintsinger6-Jan-03 8:09

clintsinger

6-Jan-03 8:09

Hi All,

I was wondering where I would find information on the techniques for debugging mutexes, semaphores, critical sections etc. I have a place in my code that blocks and locks the application. It appears to be happening randomly on a CSingleLock(&mymutex). How do I takle it and find out what the real problem is?

Cheers,
Clint

Re: Debugging Mutexes?

Tim Smith6-Jan-03 8:39

Tim Smith

6-Jan-03 8:39

1. Are you 100% positive you are always unlocking your locks?
2. Do you have any deadly embraces in your locks. (i.e. thread #1 locks lock A then lock B while thread #2 locks lock B then lock A.)

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

Re: Debugging Mutexes?

clintsinger6-Jan-03 8:47

clintsinger

6-Jan-03 8:47

As far as I know I don't have these problems. Would either problem cause random mutex lockups? I can see where #2 could potentially be the culprit as there looks like a race condition there.

Cheers,
Clint

Re: Debugging Mutexes?

Tim Smith6-Jan-03 10:16

Tim Smith

6-Jan-03 10:16

Both examples cause lockups. The first because some thread never released the mutex. The second for the race condition you saw.

Tim Smith

I'm going to patent thought. I have yet to see any prior art.

Re: Debugging Mutexes?

clintsinger9-Jan-03 7:42

clintsinger

9-Jan-03 7:42

It was a deadly embrace.

Thanks for you help.

Cheers,
Clint

Localization issue

Nish Nishant6-Jan-03 7:30

Nish Nishant

6-Jan-03 7:30

hey guys

I have run into this problem now. In my application, I use FindWindow to search for a window with a specific title text. This is all fine as long as the language is english. But what do I do for non-english versions of Windows? One solution is to have a string table with the text for the title in various languages. But is there some easier simpler way to do this that I am not aware of?

Regards,
Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Re: Localization issue

Maximilien6-Jan-03 7:34

Maximilien

6-Jan-03 7:34

Couldn't you ID the windows with an internal hard-coded (in english ) string ?

Max.

Re: Localization issue

Nish Nishant6-Jan-03 7:47

Nish Nishant

6-Jan-03 7:47

Maximilien wrote:
Couldn't you ID the windows with an internal hard-coded (in english ) string ?

Not a window created my me unfortunately. This is the IE save-as window. I am using a browser control in my dialog and using IE to save the html and all the reqd images. problem is I wanna automate this and I find the save as window, find the save button and send a click to it.

Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Re: Localization issue

nde_plume6-Jan-03 8:32

nde_plume

6-Jan-03 8:32

The IE Save As box does not save the page with images, it just saves the source HTML.

To save with images is quite an involved process, but basically what you have to do is this:

1. Open the page in your Web Browser control
2. Get the IHTMLDocument2 handle (using GetHtmlDocument)
3. Get a list of images from the IHTMLDocument2 (get_images)
4. iterate through each image:
a. Download the image to a file.
b. iterate through each IMG tag on the page, and if the
image is referenced in the HREF tag, modify the HREF
tag to point to your newly save file. (This comparison
is non trivial, because you have to connonicize both
filenames first.)
5. When you have rewritten the images, get the HTML text
from the IHTMLDocument2 and save it.

Re: Localization issue

Nish Nishant6-Jan-03 8:44

Nish Nishant

6-Jan-03 8:44

nde_plume wrote:
The IE Save As box does not save the page with images, it just saves the source HTML.

It does save images and style sheets and everything else, if you use ExecWB with OLECMDID_SAVEAS. Thanks for your suggestion though. If nothing else works I'll try that out I guess.

Nish

Author of the romantic comedy

Summer Love and Some more Cricket [New Win]

Review by Shog⁹
Click here for review[NW]

Outlook, peer connectivity

georgebrennan6-Jan-03 7:29

georgebrennan

6-Jan-03 7:29

Hi y'all I'm new here.

I've searched and searched and can't find an easy and seamless method of keeping my desktop and laptop email in sync that doesn't require an exchange server.

So I guess it looks like I have to write one myself.
Anyone got any comments, interest, warnings?

George

Control Dialogs From Main Document!

Ehsan Baghaki6-Jan-03 7:24

Ehsan Baghaki

6-Jan-03 7:24

hi. i have an Empty Document of MFC (Demo). in this Document i design a Dialog box that is open beside the Document Windows. My Dialog have a Simple Edit Box. I Creat a Class From this Dialog (CDlg) and Add a Variable to this Class for that Edit box (m_str)

how can i change this Variable in my DemoView.cpp or for example Control that if a Button is Clicked on that Dialog. (i mean i want to Control that Dialog Remotly on my DemoView.cpp)

thanx Blush | :O

-=Ehsan-de-Burge=-

Re: Control Dialogs From Main Document!

Anonymous6-Jan-03 10:24

Anonymous

6-Jan-03 10:24

I think one method is to send your CDlg a user message from your DemoView.cpp.

Last Visit: 31-Dec-99 18:00 Last Update: 9-May-24 0:04

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