Quote:Original post by legalize

Quote:Original post by ToohrVyk
The advantages of anonymous namespaces are that you don't have link-time collisions (because your identifiers are restricted to a single file) and don't pollute headers with implementation details (like a static class member or nested class would).

Interesting. I never mucked around with anonymous namespaces. How is it different from declaring the variable static, which also limits its scope to a single file?

Quote:Original post by SiCrane
Definitions inside a anonymous namespace can still have external linkage, while they don't cause name collisions at link time. This is important for template types which require names with external linkage for certain template parameters.

Quote:Well, anonymous namespaces are supposed to be used in favour of this use of "static", or so I thought until recently. But one thread made me question this, as they don't seem to map to each other completely. Read more here.

[edit:]

Quote:Original post by SiCrane
Definitions inside a anonymous namespace can still have external linkage, while they don't cause name collisions at link time. This is important for template types which require names with external linkage for certain template parameters.

Ok, thanks that explains it. [smile]

Quote:Original post by ToohrVyk

Quote:Original post by legalize
Interesting. I never mucked around with anonymous namespaces. How is it different from declaring the variable static, which also limits its scope to a single file?

It also works with classes and structures, for instance defining two distinct Visitor classes in two different files without the linker doing strange things with them (the sad part about these collisions is that you don't get a 'multiple definition' error, but rather the behaviour of the binary is erratic).

Quote:Original post by SiCrane
Definitions inside a anonymous namespace can still have external linkage, while they don't cause name collisions at link time. This is important for template types which require names with external linkage for certain template parameters.

Quote:Original post by legalize
This would be true of functions, classes and structures declared static as well, so I don't think that's the defining difference.

// File 'Main.cpp'template <const char * string>std::string bar(void) {	return string;};namespace{	extern const char message[] = "Hello";}int main(int, char **) {	std::cout << bar<message>() << std::endl;	return 0;}// File 'World.cpp"extern const char message[] = " World";

Quote:Original post by ToohrVyk

Quote:Original post by legalize
This would be true of functions, classes and structures declared static as well, so I don't think that's the defining difference.

You cannot declare a class or structure as static.

static struct{    int foo;    int bar;} foobar;