Programming Forums > Application Development > C++

Klarre · Dec 27th, 2006, 8:11 AM

Usually when I want global functions in my C++ applications I do like this:

namespace Tool
{
	static inline int foo() {}
	static inline int bar() {}
}

int main()
{
	Tool::foo();
	Tool::bar();
}

Another more common way to achieve this result is by doing it this way:

(Toggle Plain Text)

struct Tool
{
	static inline int foo() {}
	static inline int bar() {}
};

int main()
{
	Tool::foo();
	Tool::bar();
}

So to my question: Is there a difference between them (have not checked the generated code yet)? Which one should I prefer and why?
Thanks for your thoughts!

/Klarre

peaceofpi · Dec 27th, 2006, 12:20 PM

Well I'm no pro but I'm pretty sure the second one doesn't work. More like

(Toggle Plain Text)

struct Tool
{
	static inline int foo() {}
	static inline int bar() {}
};

int main()
{
	Tool hammer;
	hammer::foo();
	hammer::bar();
}

Hope I helped >_>

Klarre · Dec 27th, 2006, 2:13 PM

Quote:

Originally Posted by peaceofpi

Well I'm no pro but I'm pretty sure the second one doesn't work.

The functions are static and therefor you can call them without an object.

rsnd · Dec 27th, 2006, 3:27 PM

I think namespaces are there to resolve naming conflicts for linker in different parts of the program. For example, if you had a function with declaration "int foo() {}" in one file of your program, you shouldnot be able to have the same thing somewhere else unless its in different namespace. This is vary useful in program organization in large programs. Should be nothing more and nothing less.

grumpy · Dec 27th, 2006, 5:30 PM

Assuming all of your functions are static, there is no difference between the two approaches. A name of the struct (or class) is, in this context, a namespace. That is, among other things, why the syntax "Tool::foo();" works for calling Tool::foo() in both cases.

The example given by peaceofpi does not work, as the name of an object is not a namespace.

Eoin · Dec 27th, 2006, 6:24 PM

I would suggest going with the namespace, from a practical point it means you don't have to declare everything you want to put into 'Tool' at the one point.

Plus, stylistically, I feel the namespace version more clearly expresses your intentions. Could be just me though.

prototype_angel · Dec 29th, 2006, 2:28 AM

I would suggest going for the struct as you can do this
Tool a;
a.foo(); or something of that effect. You can also go for classes as you can inherit them. (but now you can also inherit them in structs) which can make your expansion easier. But if you won't make variables out of struct, it defeats the purpose and so it's cooler to use Namespace.

pegasus001 · Dec 29th, 2006, 10:43 AM

I guess that namespaces and structs are way too different. Most of their differences are in the way you concieve your program and the reusability of the code. You create a namespace when you create your own library or anything like that if you want to prevent nameclashes. You create struct if you have to abstract an object in the real life( because c++ treats structs and unions the same as classes).

DaWei · Dec 29th, 2006, 11:40 AM

A namespace defines a scope. All its members are public; forget access specifiers. Unlike a class or a struct, it is open. That is, you can extend it later with more definitions. Also unlike a class or struct, the closing brace does not have a following semicolon.

Dec 27th, 2006, 8:11 AM	#1
Klarre Game engine designer Join Date: May 2005 Location: Sweden Posts: 301 Rep Power: 4	namespace vs struct Usually when I want global functions in my C++ applications I do like this: (Toggle Plain Text) namespace Tool { static inline int foo() {} static inline int bar() {} } int main() { Tool::foo(); Tool::bar(); } namespace Tool { static inline int foo() {} static inline int bar() {} } int main() { Tool::foo(); Tool::bar(); } Another more common way to achieve this result is by doing it this way: (Toggle Plain Text) struct Tool { static inline int foo() {} static inline int bar() {} }; int main() { Tool::foo(); Tool::bar(); } struct Tool { static inline int foo() {} static inline int bar() {} }; int main() { Tool::foo(); Tool::bar(); } So to my question: Is there a difference between them (have not checked the generated code yet)? Which one should I prefer and why? Thanks for your thoughts! /Klarre __________________ http://www.klarre.se

Dec 27th, 2006, 12:20 PM	#2
peaceofpi hi: for(;;) goto hi; Join Date: Jun 2006 Posts: 91 Rep Power: 3	Well I'm no pro but I'm pretty sure the second one doesn't work. More like (Toggle Plain Text) struct Tool { static inline int foo() {} static inline int bar() {} }; int main() { Tool hammer; hammer::foo(); hammer::bar(); } struct Tool { static inline int foo() {} static inline int bar() {} }; int main() { Tool hammer; hammer::foo(); hammer::bar(); } Hope I helped >_> __________________ How do you play Religious Roulette? Stand around in a circle and blaspheme till someone gets struck by lightning.

Dec 27th, 2006, 3:27 PM	#4
rsnd Hobbyist Programmer Join Date: Jun 2005 Location: Helltown Posts: 162 Rep Power: 4	I think namespaces are there to resolve naming conflicts for linker in different parts of the program. For example, if you had a function with declaration "int foo() {}" in one file of your program, you shouldnot be able to have the same thing somewhere else unless its in different namespace. This is vary useful in program organization in large programs. Should be nothing more and nothing less. __________________ Spread your wings and fly! Chicken!

Dec 27th, 2006, 6:24 PM	#6
Eoin Hobbyist Programmer Join Date: Jun 2006 Location: Ireland Posts: 152 Rep Power: 3	I would suggest going with the namespace, from a practical point it means you don't have to declare everything you want to put into 'Tool' at the one point. Plus, stylistically, I feel the namespace version more clearly expresses your intentions. Could be just me though. __________________ Visit my website BinaryNotions.

Dec 29th, 2006, 10:43 AM	#8
pegasus001 Hobbyist Programmer Join Date: Nov 2006 Location: 163H Posts: 213 Rep Power: 2	I guess that namespaces and structs are way too different. Most of their differences are in the way you concieve your program and the reusability of the code. You create a namespace when you create your own library or anything like that if you want to prevent nameclashes. You create struct if you have to abstract an object in the real life( because c++ treats structs and unions the same as classes). __________________ You never test the depth of a river with both feet. The believer is happy. The doubter is wise. Free speech carries with it some freedom to listen. The next generation will always surpass the previous one. It`s one of the never ending cycles of life.

Dec 27th, 2006, 5:30 PM	#5
grumpy Programming Guru Join Date: Jun 2005 Location: Adelaide, South Australia Posts: 1,221 Rep Power: 5	Assuming all of your functions are static, there is no difference between the two approaches. A name of the struct (or class) is, in this context, a namespace. That is, among other things, why the syntax "Tool::foo();" works for calling Tool::foo() in both cases. The example given by peaceofpi does not work, as the name of an object is not a namespace.

Dec 29th, 2006, 2:28 AM	#7
prototype_angel Newbie Join Date: Dec 2006 Posts: 9 Rep Power: 0	I would suggest going for the struct as you can do this Tool a; a.foo(); or something of that effect. You can also go for classes as you can inherit them. (but now you can also inherit them in structs) which can make your expansion easier. But if you won't make variables out of struct, it defeats the purpose and so it's cooler to use Namespace.

Dec 29th, 2006, 11:40 AM	#9
DaWei Resident Grouch Join Date: Jun 2005 Posts: 6,453 Rep Power: 10	A namespace defines a scope. All its members are public; forget access specifiers. Unlike a class or a struct, it is open. That is, you can extend it later with more definitions. Also unlike a class or struct, the closing brace does not have a following semicolon. __________________ Abstraction doesn't make it impossible to write bad code; it makes it possible to write superior code. Contributor's Corner: Grumpy on C++ Exceptions DaWei on Pointers

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Programming Forums > Application Development > C++

namespace vs struct