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I was reading Item 7 of Scott Meyer's book, Effective C++ and decided to try the code. So I created my template header , a file that inherits from the template class and a driver (i.e. simple main) that tries to instantiate the new class.
I got the following errors on VC6 SP 5. Any ideas of what I am doing wrong? code is included below:
driver.cpp
c:\processdoc\c++\memorymanager\test.h(26) : error C2039: 'set_new_handler' : is not a member of 'std'
C:\ProcessDoc\C++\MemoryManager\driver.cpp(11) : while compiling class-template member function 'void *__cdecl NewHandlerSupport<class x="">::operator new(unsigned int)'
c:\processdoc\c++\memorymanager\test.h(35) : error C2039: 'set_new_handler' : is not a member of 'std'
C:\ProcessDoc\C++\MemoryManager\driver.cpp(11) : while compiling class-template member function 'void *__cdecl NewHandlerSupport<class x="">::operator new(unsigned int)'
c:\processdoc\c++\memorymanager\test.h(39) : error C2039: 'set_new_handler' : is not a member of 'std'
C:\ProcessDoc\C++\MemoryManager\driver.cpp(11) : while compiling class-template member function 'void *__cdecl NewHandlerSupport<class x="">::operator new(unsigned int)'
main.cpp
Error executing cl.exe.
MemoryManager.exe - 3 error(s), 0 warning(s)
And here is the code I have:
the main driver (driver.cpp):
#include "main.h"
void main(void)
{
x * yyy = new x();
}
the class (main.cpp & main.h):
#include "main.h"
x::x()
{
}
x::~x()
{
}
void x::test()
{
}
//////main.h
#include "test.h"
class x : public NewHandlerSupport<x>
{
public:
x();
~x();
void test ();
private:
};
the template (right off SM's book)..I called it test.h :
#include <new>
template<class t="">
class NewHandlerSupport {
public:
static new_handler set_new_handler(new_handler p);
static void * operator new(size_t size);
private:
static new_handler currentHandler;
};
template<class t="">
new_handler NewHandlerSupport<t>::set_new_handler(new_handler p)
{
new_handler oldHandler = currentHandler;
currentHandler = p;
return oldHandler;
}
template<class t="">
void * NewHandlerSupport<t>::operator new(size_t size)
{
new_handler globalHandler =
std::set_new_handler(currentHandler);
void *memory;
try {
memory = ::operator new(size);
}
catch (std::bad_alloc&)
{
std::set_new_handler(globalHandler);
throw;
}
std::set_new_handler(globalHandler);
return memory;
}
// this sets each CurrentHandler to 0
template <class t="">
new_handler NewHandlerSupport<t>::currentHandler;
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Its telling you that set_new_handler function is not a member of the namespace std. Instead of std::set_new_handler you should use NewHandlerSupport::set_new_handler
Bret Faller
Odyssey Computing, Inc.
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confused:
I have a WTL project where I have placed two TrackBarCtrl's on it using the
Create() function. I have a Message handler for the WM_HSCROLL event.
My problem is that I am not sure how to determine which trackbar fired the event as they
both call the same event handler. The documentation says that the lParam contains the handle
but it doesn't match up with my variables.
Please Help
Thanks,
Clint Singer
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You're saying your two Trackbars have HWND's different to the one passed in as lParam ?
Christian
this space for rent
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My code looks something like this:
CTrackBarCtrl* slider;
CTrackBarCtrl* speed;
...
BEGIN_MSG_MAP(CDVMSPlayerView)
MESSAGE_HANDLER(WM_PAINT, OnPaint)
MESSAGE_HANDLER(WM_CREATE, OnCreate)
MESSAGE_HANDLER(WM_DESTROY, OnDestroy)
MESSAGE_HANDLER(WM_HSCROLL, OnSlide)
COMMAND_ID_HANDLER(IDC_PLAY, OnPlay)
END_MSG_MAP()
...
slider = new CTrackBarCtrl();
rect.SetRect(CPoint(0, 260), CPoint(320, 290));
slider->Create(m_hWnd, &rect, NULL, WS_CHILD | WS_VISIBLE, NULL, (HMENU) IDC_SLIDER, NULL);
speed = new CTrackBarCtrl();
rect.SetRect(CPoint(0, 300), CPoint(50, 320));
speed->Create(m_hWnd, &rect, NULL, WS_CHILD | WS_VISIBLE, NULL, (HMENU) IDC_SPEED, NULL);
...
LRESULT OnSlide(UINT uMsg, WPARAM wParam, LPARAM lParam, BOOL& bHandled)
{
// Need to determine whether slider or speed fired the event
if (player && player->IsRunning()) {
//if ((void*)lParam == slider) {
// player->Pause();
// player->SetFrame(slider->GetPos());
Invalidate(false);
//}
//else if ((void*)lParam == speed){
//player->SetWaitTime((21 - speed->GetPos()) * 100);
//}
}
return 0;
}
I must be doing something wrong here. If it is possible to use a switch-case clause
that would be better but slider and speed aren't constants.
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Try getting rid of the (void*) cast (why ???), and dereference your variables. CTrackbarCtrl will almost certainly offer operator HWND, but CTrackbarCtrl* most certainly will not.
Christian
As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.
Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.
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You're comparing an HWND with a C++ object pointer, which obviously aren't the same creatures. Do something like:
if ( (HWND)lParam == slider->m_hWnd )
--Mike--
http://home.inreach.com/mdunn/
This posting is provided "as was" with no warranties, guarantees, lotteries, or any of those little bags of peanuts you get on planes. You assume all risk for crossing the street without holding mommy's hand. © 2001 Mike's Classy Software. Member FDIC. If rash develops, discontinue use.
![Heart | [heart]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/love.gif) your ![Green Alien | [Alien]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/alien.gif) with ![Good Stuff | [The good stuff]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/vegemite.gif) and ![Beer | [beer]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/beer.gif)
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Thanks, that did the trick.
Cheers,
Clint
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Just for my own info, does that mean that dereferencing the slider * wouldn't result in a HWND ? I'm writing my own control classes at the moment and all have operator HWND defined, I'm surprised at the possibility that the M$ classes don't do the same thing ?
Christian
As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.
Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.
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When we dereference the pointer all we get is the pointer to the object it self - not the m_hWnd that it contains. You could get the hWnd when you call the create function ie.
CTrackbarCtrl *tb;
HWND hwnd;
hwnd = tb->Create(...);
but that means you would have to carry around two variables when the hwnd is already being carried around in the class provided by WTL.
Cheers,
Clint 
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So WTL doesn't offer operator HWND on these items, nor does it have a m_hWnd variable ? I find that highly unlikely.
I've just had a look at the WTL source, and they do indeed keep the HWND as a variable called m_hWnd, so that is what you need.
Christian
After all, there's nothing wrong with an elite as long as I'm allowed to be part of it!! - Mike Burston Oct 23, 2001
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Hey Guys
When i try and use this function
CertGetNameString()
i get a undeclared identifier message when i compile yet msdn says this is defined in wincrypt.h which i have included has anyone got any ideas
peter
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As this function requires Windows 98/ME, I'd say for sure to get access to it you'll need to install the Platform SDK.
Christian
As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.
Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.
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A co-worker and I were having a discussion about what sync object to use for a particular case. The senerio is as follows:
Read an item from a list
Write data to a device, using a sperate thread
Wait for write to complete
Repeat until list is complete
He designed the above to use a semaphore where I pointed out that an event would be more appropriate in this case. His arguement was that there was no difference in the how the two were created, used, etc. He could not seem to handle the statement "why have two objects to do the same thing".
Could anyone comment on the overhead, resource usage, etc. of the two objects.
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I've a control that is used to update real-time stock quotes. The control uses the CMemDC class to draw to avoid the flickering but i still see the control flicker. Essentially, the drawing code looks like this (borrowed the technique from Chris' Grid control)
XYZControl::OnPaint()
{
CPaintDC dc(this);
if (m_bDoubleBuffer)
{
CMemDC memDC(&dc);
OnDraw(&memDC);
}
else
OnDraw(&dc);
}
XYZControl::OnDraw(CDC* pDC)
{
}
One interesting thing that i noticed while debugging was that the GetClipBox() call in MemDC contructor returns a empty rectangle. Suspecting this could mean trouble? Any thoughts on what should i check/verify? 
Thanks
Chen Venkataraman
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Shouldn't that be TRUE? Here's the snippet from MSDN for WM_ERASEBKGND :
<br />
An application should return nonzero in response to WM_ERASEBKGND if it processes the message and erases the background; this indicates that no further erasing is required. If the application returns zero, the window will remain marked for erasing. (Typically, this indicates that the fErase member of the PAINTSTRUCT structure will be TRUE.)<br />
Anyway, I've handled the WM_ERASEBKGND message & returned both FALSE & TRUE but it appears that it doesn't matter - the control still flickers.
Chen Venkataraman
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Returning FALSE follows the MSDN docs - after all, you do not erase the background just by returning FALSE from the empty handler.
BTW: Use GetClipBox with a paint DC, not with a memory DC.
Tomasz Sowinski -- http://www.shooltz.com
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The way I always did this was to draw the control to a memory DC, THEN call CPaintDC, THEN draw the control. CPaintDC causes the area to be erased, although it is reasonable to suggest that overriding OnEraseBackground to not call the parent method would solve this also.
When you overrode WM_ERASEBACKGROUND, did you still call the base method ? If so, don't if you don't want the background erased.
Christian
As I learn the innermost secrets of the around me, they reward me in many ways to keep quiet.
Men with pierced ears are better prepared for marriage. They've experienced pain and bought Jewellery.
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Hello,
As a part of the college lab work I have to write a client and a server using MFC. The prof explained the whole stuff briefly, and I recall him having talked about threads etc. The client/server have to use the UDP protocol and be able to transfer files (even big ones).
Can someone tell me how to do this? or where I can find relevant resources? I dont know how to analyse the problem.
Thanks,
Mike
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Hi, does anybody know how can I hide the main frame in a MDI app?? Tnx
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