C / C++ / MFC

Re: How can I use different typfaces for several static controls in a dialog and change them at runtime?

20-Aug-07 6:08

min_2_max wrote:
It seems to be a stupid question.

No. Maybe a stupid answer though.

Did you get it working?

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

min_2_max20-Aug-07 14:26

min_2_max

20-Aug-07 14:26

There seems still to be some problem. Smile | :)

Max

Limiting access to a class

Waldermort16-Aug-07 14:54

16-Aug-07 14:54

Lets say I have 2 classes derived from the same base. Within the base I want to have a private member. But, when one derived type is passed to another, I want that instance to be able to gain access. ie...

class Base
{
protected:
    int iSomeVal;
}

class A : public Base
{
    void Copy( Base* pBase )
    {
        // How can I get around the error here without using a public member?
        iSomeVal = pBase->iSomeVal;
    }
}

class B : public Base
{
///
}

main()
{
    A foo;
    B bar;
    foo.Copy( &bar );
}

cp987616-Aug-07 15:02

cp9876

16-Aug-07 15:02

Sounds like you need a protected member, accessible to derived classes but not outside.

Peter
"Until the invention of the computer, the machine gun was the device that enabled humans to make the most mistakes in the smallest amount of time."

Waldermort16-Aug-07 15:17

16-Aug-07 15:17

protected only works for derived types, the member would be seen as private when trying to access from outside ( which is what I am doing if you look again ).

Mark Salsbery16-Aug-07 15:17

16-Aug-07 15:17

You could use friend:

class A;

class Base
{
private:
    int iSomeVal;

friend A;
};

class A : public Base
{
public:
    void Copy( Base* pBase )
    {
        // How can I get around the error here without using a public member?
        iSomeVal = pBase->iSomeVal;
    }
};

class B : public Base
{
///
};

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Waldermort16-Aug-07 15:22

16-Aug-07 15:22

That works, but rather than having a forward decleration, I made it a friend of itself ( must be a loner Poke tongue | ;-P

)

Mark Salsbery16-Aug-07 15:25

16-Aug-07 15:25

WalderMort wrote:
but rather than having a forward decleration, I made it a friend of itself

You did what? May I see it please? Smile | :)

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Waldermort16-Aug-07 15:29

16-Aug-07 15:29

C'mon, it's 9:30 in the morning and I didn't sleep yet, is my humour really that bad Unsure | :~

Mark Salsbery16-Aug-07 15:30

16-Aug-07 15:30

C'mon, it's 6:30 pm and I'm tired LOL!

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Mark Salsbery16-Aug-07 15:36

16-Aug-07 15:36

I just realized you said you didn't sleep yet OMG | :OMG:

I've only been up 12 hours, but it still went right over my head Smile | :)

Cheers!

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

Waldermort16-Aug-07 15:40

Overrides-Messages concept in MFC

16-Aug-07 15:40

I wanted to get these sets of classes finished, but right now I'm just too tired to even look at the code. I think I'm gonna call it a night, day, mornin... oh whatever...

sawerr16-Aug-07 11:37

sawerr

16-Aug-07 11:37

Hi I have a basic question about MFC.
There are methods in MFC which are in overrides section or Message Section.
What is the difference?
For example: For CView class
OnDraw is in overrides section. But OnDrawItem is in messages section.
Why is it so?
What is the concept/logic behind this?
I hope i could explain my question.

Thanks

Mark Salsbery16-Aug-07 13:17

16-Aug-07 13:17

The overrides section implies virtual methods that derived classes can override and/or
the class has derived from its base class.

The messages section (which I don't see in the VS 2005 MFC reference) would be for
methods that handle Windows messages (WM_xxx).

A select few Windows messages are handled and rerouted via a virtual
method. CDialog::OnInitDialog() is one (in fact, I can't think of any others off hand).

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

sawerr16-Aug-07 14:03

sawerr

16-Aug-07 14:03

Thank you.
Overrides are virtual functions as you said. But i couldn't understand the rule for a event/function/message etc.. is defining in overrides part or Messages part in Properties window.
I asked for the concept.
For example for CMainFrame class; OnNotify is virtual(in Overrides) but there is a window message that is WM_NOTIFY so why isn't it in messages section in Properties window.

Thanks again.

Mark Salsbery16-Aug-07 14:27

16-Aug-07 14:27

WM_NOTIFY/OnNotify() is another message that MFC catches and reroutes virtually.
WM_COMMAND is another.

I'm not sure why some are done this way and others are not. I can see why every possible
WM_xxx message isn't dispatched through a virtual call, but I'm unsure why every message
isn't handled the same. Maybe to insure MFC gets first crack at those messages?
I guess it works out nicely internally in MFC, but for us it's just inconsistent.

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

bob1697216-Aug-07 14:22

bob16972

16-Aug-07 14:22

The thing I don't understand is why the overrides don't populate when user classes derived from user classes have virtual methods, even if they are derived from CObject. It doesn't list the virtual methods except those of CObject. It's almost like it's based on a lookup table and is hardly dynamic.

Mark Salsbery16-Aug-07 14:49

16-Aug-07 14:49

Do you mean virtual functions that we add - so we could go to the overrides list and
click to insert a stub in the source code?

Mark

Mark Salsbery
Microsoft MVP - Visual C++
Java | [Coffee]

bob1697216-Aug-07 15:53

bob16972

16-Aug-07 15:53

Virtual functions that we add to our base classes.

If we create a base class (derived from CObject for instance), add some virtual functions, then derive a class from it, select the derived class, and in the overrides list, only those virtual functions that are in CObject show up currently.

I had expected it to show the virtual functions from any super class but it doesn't appear to work that way.

Not that it's really a big deal, but it struck me as odd. Maybe I'm missing something but I played with a few variations of class hierarchies and it does not appear to pick up on them.

Just a passing comment, by the way.