C / C++ / MFC

Re: Developing a gui toolkit

27-Dec-09 16:10

I found this open source GUI toolkit based on OpenGL - LibUFO[^]

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

bi0phaz327-Dec-09 16:12

bi0phaz3

27-Dec-09 16:12

Thank you kindly. I hadn't thought of looking into open source toolkits and reverse engineering them. ^^;; I'll get right on that.

Re: Developing a gui toolkit

«_Superman_»27-Dec-09 16:15

Waking from Sleep/Hybernation

27-Dec-09 16:15

I guess this would be your best bet, unless you can get hold of a book that is specific to GUI toolkits.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Bram van Kampen27-Dec-09 11:47

27-Dec-09 11:47

Hi,

Is there a Windows Message being broadcast by the system when it enters/leaves Sleep/Hibernation Mode.

Thanks, Smile | :)

Bram van Kampen

«_Superman_»27-Dec-09 15:08

27-Dec-09 15:08

WM_POWERBROADCAST[^]

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

Bram van Kampen28-Dec-09 0:47

28-Dec-09 0:47

Thanks,

Fits the bill like a glove.

Rose | [Rose]

Bram van Kampen

Nelek28-Dec-09 0:55

Nelek

28-Dec-09 0:55

If the previous answer helped you, please click on "Good Answer" and give it the deserved merit Smile | :)

Regards.
--------
M.D.V. Wink | ;)

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
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Bram van Kampen28-Dec-09 1:37

How to get the parent proccess's path

28-Dec-09 1:37

Thanks,

You're right,
Just did so.
Sniff | :^)

Bram van Kampen

Joseph Marzbani26-Dec-09 21:38

Joseph Marzbani

26-Dec-09 21:38

I want to run an application (see child) so that it can get the path of the current process (see parent). How?

Thank you masters!

Stephen Hewitt26-Dec-09 23:09

Stephen Hewitt

26-Dec-09 23:09

Your question is a little unclear. Why not simply pass the path to the process on the command line?

Steve

rp_suman27-Dec-09 0:25

rp_suman

27-Dec-09 0:25

Are you looking for GetModuleFileName Function?

You can get the path of the executable file of the current process using above function.
Sample code:

TCHAR szBuff[512];
GetModuleFileName(0, szBuff, 512);

--
"Programming is an art that fights back!"

Bram van Kampen27-Dec-09 11:50

27-Dec-09 11:50

Well,

I would use GetModuleFileName() in the Parent process, and stuff it into the Environment of the Child Process:-
PARENTPROCESS=C:\Program Files\etc...
The Child Process can then queery the Environment, to get the Paren Process Name back.

Smile | :)

Bram van Kampen

raja jamwal31-Dec-09 8:47

raja jamwal

31-Dec-09 8:47

Well you can use getcurrentdirectory to get the directory where the application was executed only if the parent process haven't changed that.

Bram van Kampen3-Jan-10 23:48

3-Jan-10 23:48

raja jamwal wrote:
Well you can use getcurrentdirectory to get the directory where the application was executed only if the parent process haven't changed that.

No, Not Realy. getcurrentdirectory does exactly what it says. That is not nescessarily the same dir as where the exe is located.

That's why I use GetModuleFileName();
Smile | :)

Bram van Kampen

raja jamwal9-Jan-10 4:06

raja jamwal

9-Jan-10 4:06

yeah i know, the current directory variable attached with the module can be changed.

Bram van Kampen9-Jan-10 16:10

good encapsulation technique ? [modified]

9-Jan-10 16:10

Amen

Bram van Kampen

doug2526-Dec-09 10:03

doug25

26-Dec-09 10:03

EDIT:

The solution to my problem is to declare certain member variables as protected and use get and set functions to work with them. The reason I was reluctant to do this was because I thought it would be better to be able to read from protected variables directly but the speed difference compared to using a function to read a variable is no different, or so minute that it will never affect performance in any way. This is the standard for working with encapsulated variables so it's definately better than what I was doing before and allows for proper encapsulation.

I've decided to scrap the code below, what I thought was a good solution, because it's poor style and few people would understand exactly the point of it if they were to attempt to edit code that uses it :

//#define EDITINGCODE

#ifdef EDITINGCODE
	#define PROTECTED protected
#else
	#define PROTECTED public
#endif

// Using PROTECTED allows the declaration of
// member variables that shouldn't be modified
// without using member functions
// while they can be read from
// within any scope

class Class1
{
PROTECTED:
	int var;
};

Quite often I only want to change member variables of classes using member functions and prevent these from being changed elsewhere in a program but still allow access to the variables data.

A common programming technique for this effect is to have a get function in a class that returns the value of a private / protected variable. But I figured that this technique could be inefficient when lots of accesses have to be made to those encapsulated variables because functions must be used to retrieve data.

So I've come up with a different solution that might be better. Hopefully i'm explaining ok what I want to achieve.

I want to know whether this technique is good or not ?

Basically, all I have to do is create a header file or a macro something like this :

#define FRIENDTOALL \
	friend Class1; \
	friend Class2; \
	friend int function(); \
	friend int main();

So it contains all the classes and functions in the program.
And then place the FRIENDTOALL macro in each class that contains encapsulated members.
That way it's possible to access private and protected variable members from anywhere in the program and still be able to see that they are not meant to be modified without using a class's functions.

Would it be wise to use this technique so I can see what variables are not to be modified without using member functions or are there any noticable draw backs to doing it this way ?

modified on Monday, December 28, 2009 9:46 AM

Jimmanuel26-Dec-09 14:44

Jimmanuel

26-Dec-09 14:44

I wouldn't really call this a good encapsulation technique, it's more like an anti-encapsulation technique. The whole point of making things protected and private is so that other classes can't access them directly, making every class a friend blows that idea out of the water. At that point why not just make everything public?

doug25 wrote:
prevent these from being changed elsewhere in a program

Oh yeah, that's why we don't want to make everything public.

Especially with judicious use of inlining, the performance hit of using getters/setters is minimal in the grand scheme of things.

Badger | [badger,badger,badger,badger...]

Badger | [badger,badger,badger,badger...]

«_Superman_»26-Dec-09 16:43

Re: good encapsulation technique ? [modified]

26-Dec-09 16:43

doug25 wrote:
But I figured that this technique could be inefficient when lots of accesses have to be made to those encapsulated variables because functions must be used to retrieve data.

I think you're wrong here in the first place.
The latest compilers will definitely optimize the function calls with direct access.
You should turn on full optimization and check the assembly output that is generated.

I recommend you do not worry about optimization unless you're actually facing some sort of bottle neck.
'Cause you're simply ruining code encapsulation and more than that readability which will ultimately lead to a maintenance nightmare.

«_Superman_»
I love work. It gives me something to do between weekends.

Microsoft MVP (Visual C++)

doug2527-Dec-09 0:05

doug25

27-Dec-09 0:05

Thanks for the comments,

EDIT:

with optimizations turned on, using value = var.var is 1.3 times faster than using a function like value = var.var(). But at millionth's of a second for getting a value 900 million times.

~~woops, I used an unsigned int for a very big loop, so the value wasn't actually retrieved 900 million times~~. I recalculated (incrimenting a double for loops) and found that one hundred million value = var.var is 1.0366 times faster than one hundred million value = var.var()

oh, unsigned ints have range 0 to 4,294,967,295

So I guess there isn't much difference in speed using a function to retrieve values. Smile | :)

nevertheless, that was really silly of me, I could easily achieve the same effect as what I originally intended by :

class Class1
{
protected:
//public:
	int var;
}

and then uncomment public: when building a project.

The reason I would want to do this is because to me, protected values should be values that can be read from but not written to (outwidth the class), so when editing using intellisense it's useful for me to see what variables I intend to be protected in the "Let me know when it's ok and when it's not ok to change them" sense.

But I would probably only do this when i'm editing code, otherwise make variables always public if someone else is editing it. see what I mean.

but given that the speed difference of using a get function is so minute, I'll probably start using get functions. though for certain special cases I might want to treat a variable as "protected" but still be able to change it in different scopes so my technique might be useful there.

Cedric Moonen27-Dec-09 1:53

Cedric Moonen

27-Dec-09 1:53

doug25 wrote:
protected values should be values that can be read from but not written to (outwidth the class)

You should revise a bit your C++ books Smile | :)

. Protected doesn't mean that at all. It simply means that the classes which are inheriting from your class will have access to all protected members (as if they were public) but the rest of your program won't be able to access to members. If a member is private, then the inheriting classes can't access these members. (This is only valid for public inheritance, which is the most common used).

Anyway, what you are doing makes the code horribly hard to maintain because if another programmer reads your code, he won't be able to understand anything of what you were trying to do. As others already said, use getters/setters and turn on optimization, this is by far the best solution because it is standard.

Cédric Moonen
Software developer

Charting control [v2.0]
OpenGL game tutorial in C++

doug2527-Dec-09 2:05

doug25

27-Dec-09 2:05

yes, I know what protected means Smile | :)

, I think for projects that aren't personal i'll use the get standard, but I'm not keen on it because sometimes it could be useful to be able to modify protected members in global scope, so I've come up with the following to compensate for the rare circumstances :

//#define EDITINGCODE

#ifdef EDITINGCODE
	#define PROTECTED protected
#else
	#define PROTECTED public
#endif

// Using PROTECTED allows the declaration of
// member variables that shouldn't be modified
// without using member functions
// while they can be read from
// within any scope

class Class1
{
PROTECTED:
	int var;
};

thanks for the advice however