namespaces or static classes ?? you decide

Hussain Hani · 07-10-2009, 06:30 PM

In a book i'm reading about C++ software programming called :
Large-Scale C++ Software Design

The author does not utilize namespaces at all specially that he is taking about how to use C++ for extensive, large projects

instead, he uses static classes like this:

Code:

class HussainLib
{
	HussainLib(); //no class instantiation meant

	//functions
public:
	static void bubble_sort(int* list, int size);
	static void arithmetic(int x, int y, int arith);
                //blah blah blah

	//data
public:
	static const double PI();
	static const double e();
                //blah blah blah
};

and of course you would call them like this:

Code:

const double PI = HussainLib::PI()

what do you think? is it more practical than namespaces ?
I find it a very good way to hide data and functions for programmers working together

scwizzo · 07-10-2009, 07:03 PM

I think it depends on the needs and uses of the class/namespace. I know of some software APIs/Devkits that have classes within namespaces to differentiate between which one you want. Example: if you have a class that decodes audio formats like mp3, or wave, or ogg, and the class has the same function names/declaration, what then? Namespace the class so the compiler knows which class you want to use.

IMHO, it's preference.

grumpy · 07-10-2009, 11:02 PM

Quote:

Originally Posted by Hussain Hani

The author does not utilize namespaces at all specially that he is taking about how to use C++ for extensive, large projects

what do you think? is it more practical than namespaces ?
I find it a very good way to hide data and functions for programmers working together

As a matter of fact, there is no real distinction with standard C++. All static and non-static members of a class exist within a namespace with the same name as the class.

There was a distinction with some older (almost antique) compilers, as early (draft) versions of the C++ standard supported classes but did not specifically support the concept of namespaces.

**laserlight** · 07-10-2009, 11:02 PM

Quote:

Originally Posted by Hussain Hani

The author does not utilize namespaces at all specially that he is taking about how to use C++ for extensive, large projects

That is because C++ was standardised after that book was published, and though I have little knowledge of the state of C++ at the time, my guess from my use of MVSC6 is that the namespace feature in its current form was far from widely adopted at the time of writing of that book.

**Fordy** · 07-11-2009, 01:27 AM

If you are going to use this trick, then why not look up the singleton pattern.

**laserlight** · 07-11-2009, 02:12 AM

Quote:

Originally Posted by Hussain Hani

what do you think? is it more practical than namespaces ?

Either way seems practical to me. However, consider that you can "re-open" a namespace, but have to change the class definition to add a new static member function. Also, consider that you can use using declarations and using directives with namespaces where appropriate and convenient, but not so for classes, where using declarations are mainly used to make visible names from a base class that would otherwise be hidden.

There is also the option of using an anonymous namespace in a source file to hold functions that are implementation detail and yet do not need direct access to the internals of the class(es) being implemented.

Quote:

Originally Posted by Hussain Hani

I find it a very good way to hide data and functions for programmers working together

Eh, but the idea is to group, not hide, as opposed to "normal" usage of classes where the class serves as an abstraction.

Quote:

Originally Posted by Fordy

If you are going to use this trick, then why not look up the singleton pattern.

I do not think that that would be correct: from what I understand, the idea here is to use a class that cannot be instantiated to provide a namespace for a set of (otherwise) free functions.

**Fordy** · 07-11-2009, 03:04 AM

Quote:

Originally Posted by laserlight

I do not think that that would be correct: from what I understand, the idea here is to use a class that cannot be instantiated to provide a namespace for a set of (otherwise) free functions.

Maybe, but personally I'd rather stick with the singleton pattern - it achieves pretty much the same thing and has a few added extras

anon · 07-11-2009, 03:13 AM

Why do I need the instance to call BubbleSort?

Code:

MyLib::GetInstance().BubbleSort(data);

EVOEx · 07-11-2009, 04:35 AM

I have seen cases where a class with static functions was more useful. I can't think of the exact situation, but I remember they were two "namespaces" with similar functionality, however which was to be used depended on something (the system, the configuration, whatever). In this case, a class was better because I could instantiate the class and pass it to a function and call the functions of the class inside that function. It was the best design I could think of at that point.

**Bubba** · 07-11-2009, 11:20 AM

I hope I never have to maintain code like that. Too many statics always throws a red flag for me. Seems pointless to me since there are several design patterns out there that do much the same. If you are going to do things that way why use C++ at all?

07-10-2009, 06:30 PM	#1
Hussain Hani "Why use dynamic memory?" Join Date: Aug 2006 Posts: 179	namespaces or static classes ?? you decide In a book i'm reading about C++ software programming called : Large-Scale C++ Software Design The author does not utilize namespaces at all specially that he is taking about how to use C++ for extensive, large projects instead, he uses static classes like this: Code: class HussainLib { HussainLib(); //no class instantiation meant //functions public: static void bubble_sort(int* list, int size); static void arithmetic(int x, int y, int arith); //blah blah blah //data public: static const double PI(); static const double e(); //blah blah blah }; and of course you would call them like this: Code: const double PI = HussainLib::PI() what do you think? is it more practical than namespaces ? I find it a very good way to hide data and functions for programmers working together __________________ "C makes it easy to shoot yourself in the foot; C++ makes it harder, but when you do, it blows away your whole leg."-Bjarne Stroustrup OS: Microsoft XP Media Center IDE: Microsoft Visual Studio 2005 pro edition Current Porject: Developing a 2D card game...
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07-10-2009, 07:03 PM	#2
scwizzo Registered User Join Date: Mar 2007 Posts: 333	I think it depends on the needs and uses of the class/namespace. I know of some software APIs/Devkits that have classes within namespaces to differentiate between which one you want. Example: if you have a class that decodes audio formats like mp3, or wave, or ogg, and the class has the same function names/declaration, what then? Namespace the class so the compiler knows which class you want to use. IMHO, it's preference. __________________ home page (new layout)
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07-11-2009, 01:27 AM	#5
Fordy &TH of undefined behavior Join Date: Aug 2001 Posts: 5,183	If you are going to use this trick, then why not look up the singleton pattern. __________________ "If A is success in life, then A equals x plus y plus z. Work is x; y is play; and z is keeping your mouth shut." Albert Einstein (1879 - 1955) Board Rules
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07-11-2009, 04:35 AM	#9
EVOEx Registered User Join Date: Oct 2008 Posts: 452	I have seen cases where a class with static functions was more useful. I can't think of the exact situation, but I remember they were two "namespaces" with similar functionality, however which was to be used depended on something (the system, the configuration, whatever). In this case, a class was better because I could instantiate the class and pass it to a function and call the functions of the class inside that function. It was the best design I could think of at that point.
EVOEx is offline

07-11-2009, 11:20 AM	#10
Bubba Super Moderator Join Date: Aug 2001 Posts: 7,470	I hope I never have to maintain code like that. Too many statics always throws a red flag for me. Seems pointless to me since there are several design patterns out there that do much the same. If you are going to do things that way why use C++ at all? __________________ If you aim at everything you will hit something but you won't know what it is.
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