C / C++ / MFC

7-Jan-02 10:22

Here's the scenerio

I have created a app using appwiz(VC++6) and have selected the doc/view arch. Now what i'd like to have is custom app wide properties in the CMainFrame class which are modified via dialogs. The dialog is constructed as a member of CMainFrame. I can transfer data from the dialog to CMainFrame no probs, but how can i do the same for my custom CView class. CView has it's own custom members used for drawing, but part of the drawing process requires info stored in CMainFrame. You swap data between CView and CDocumnet with the GetDocument() is there anyway to get the data(custom member) from CMainFrame. I managed to used globals, but doesn't this defeat the purpose OOP? I would like a more OOD<smiles> To do this would i have to construct CView and CDocument in CMainFrame rather than settle for the appwiz default of dynamic creation using CDocTemplate() and such...?

pardon my lack of clarity

TIA

Alex deltabravo@mb.sympatico.ca Confused | :confused:

"An expert is someone who has made all the mistakes in thier field" - Niels Bohr

J Patel7-Jan-02 10:31

J Patel

7-Jan-02 10:31

You can do this in your CView derived class.

((CMainFrame*)AfxGetMainWnd())->m_yourCustomMemberVariable;

HTH

Jignesh

alex.barylski7-Jan-02 11:28

7-Jan-02 11:28

I tried the folowing, however got a compile error

'variable' is not a member of 'CWnd'

Doesn't the following return a pointer to generic CFrameWnd rather than derived?

Any suggestion...?
Smile | :)

"An expert is someone who has made all the mistakes in thier field" - Niels Bohr

J Patel7-Jan-02 11:30

J Patel

7-Jan-02 11:30

Did you try (CMainFrame*)AfxGetMainWnd()->variable; ?

Jignesh

alex.barylski7-Jan-02 11:50

7-Jan-02 11:50

I used a cast, included the header but still came up with m_Variable is not a member of CWnd.

I even tried instantiating a new CMainFrame obj(however could do it, cuz CMainFrame has protected constructor) but then it would be a differ instance right...? which would mean incorrect data.

Is is even possible to use a object that isn't constructed as a data member from that class...? If that even makes sense...<smiles>

I can use AfxGetMainWnd() but only to call CMainFrame's native functions like resize, but the methods and members i've added in my custom class don't appear in the auto-popup...

Being that the CView,CDocument and CFrameWnd object are created dynamically at runtime via the AddDocTemplate funtion in derived app InitInstance() is there any way i can get hold of pointer to any of these objects using RTTI..?

"An expert is someone who has made all the mistakes in thier field" - Niels Bohr

Derek Waters7-Jan-02 12:11

Derek Waters

7-Jan-02 12:11

I think you'll just need an extra set of brackets...

int viMySetting = ((CMainFrame *)AfxGetMainWnd())->m_iMySetting;

Hope this helps.

------------------------
Derek Waters
derek@lj-oz.com

alex.barylski7-Jan-02 12:23

Variable Length Function parameter list

7-Jan-02 12:23

Try'd it and i finally got passed the compiler warning and had the popup assitance window show my custom members...

That worked so hopefully will the final result...haven't tested that yet...to excited, but soon

Thanx alot

"An expert is someone who has made all the mistakes in thier field" - Niels Bohr

slacker7-Jan-02 9:47

slacker

7-Jan-02 9:47

Does anybody know how to get the number of arguments from a variable length function parameter list? I can't seem to find any documentation anywhere about how to get then number or arguments, without the number of args being a parameter itself.

Joaquín M López Muñoz7-Jan-02 10:00

Joaquín M López Muñoz

7-Jan-02 10:00

You can't. The number (and type) of arguments has to be deduced from one of the non-variable arguments supplied, like, for instance, printf does with its first format argument.

Joaquín M López Muñoz
Telefónica, Investigación y Desarrollo

Todd Smith7-Jan-02 11:47

Todd Smith

7-Jan-02 11:47

Actually, you can.

int CountArgs(char* unused, ...)
{
	int count = 0;

	va_list args;
	va_start(args, unused);

	for (char* cp = va_arg(args, char*); cp; cp = va_arg(args, char*))
	{
		count++;
	}
	
	va_end(args);

	return count;
}

int main()
{

	int numArgs = CountArgs("blah", "1", "2", "3", "4");

	return 0;
}

You could also use the first variable to indicate how many variables you are passing in.

CountArgs(int numArgs, ...);

Todd Smith

Tim Smith7-Jan-02 11:58

Tim Smith

7-Jan-02 11:58

That the will NOT work reliably. If you look at the code generated, there isn't a NULL pushed onto the stack. Thus, just by luck does this work when it does.

19:   int main()
20:   {
004010B0   push        ebp
004010B1   mov         ebp,esp
004010B3   sub         esp,44h
004010B6   push        ebx
004010B7   push        esi
004010B8   push        edi
004010B9   lea         edi,[ebp-44h]
004010BC   mov         ecx,11h
004010C1   mov         eax,0CCCCCCCCh
004010C6   rep stos    dword ptr [edi]
21:       int numArgs = CountArgs("blah", "1", "2", "3", "4");
004010C8   push        offset string "4" (00422030)
004010CD   push        offset string "3" (0042202c)
004010D2   push        offset string "2" (00422028)
004010D7   push        offset string "1" (00422024)
004010DC   push        offset string "blah" (0042201c)
004010E1   call        @ILT+5(CountArgs) (0040100a)
004010E6   add         esp,14h
004010E9   mov         dword ptr [ebp-4],eax
22:       return 0;
004010EC   xor         eax,eax
23:   }
004010EE   pop         edi
004010EF   pop         esi
004010F0   pop         ebx
004010F1   add         esp,44h
004010F4   cmp         ebp,esp
004010F6   call        __chkesp (00401120)
004010FB   mov         esp,ebp
004010FD   pop         ebp
004010FE   ret

Specifically in this case, the only reason this works is because EDI was 0.

Tim Smith
Descartes Systems Sciences, Inc.

Todd Smith7-Jan-02 12:33

Todd Smith

7-Jan-02 12:33

Tim is correct.

So I would either pass the # args as the first parameter (what I usually do anyways) or if it makes sense require the last parameter to be 0.

Todd Smith