C++Talk.NET C++ language newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Nested namespaces definition          C++Talk.NET Forum Index -> C++ language, library and standards View previous topic :: View next topic   Author Message adeht Guest Posted: Tue Apr 13, 2004 8:18 pm    Post subject: Nested namespaces definition Why won't the standard allow the following? namespace MyNS::Private { // ... } --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Steven T. Hatton Guest Posted: Wed Apr 14, 2004 5:44 pm    Post subject: Re: Nested namespaces definition adeht wrote: Quote: Why won't the standard allow the following? namespace MyNS::Private { // ... } This is something Mathematica supports for its packages. I've wondered the same thing. I haven't proposed this for C++ simply because I had not come across a use for it in C++. How would such a construct benefit the language? -- STH http://www.kdevelop.org http://www.suse.com http://www.mozilla.org --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top adeht Guest Posted: Wed Apr 14, 2004 6:58 pm    Post subject: Re: Nested namespaces definition ""Steven T. Hatton"" <hattons (AT) globalsymmetry (DOT) com> wrote Quote: This is something Mathematica supports for its packages. I've wondered the same thing. I haven't proposed this for C++ simply because I had not come across a use for it in C++. How would such a construct benefit the language? I didn't search, sorry about that. Here's the proposal: http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/papers/2003/n1524.htm You can read about the possible uses for that in the paper. --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Carl Daniel Guest Posted: Thu Apr 15, 2004 5:01 am    Post subject: Re: Nested namespaces definition "adeht" wrote: Quote: Why won't the standard allow the following? namespace MyNS::Private { // ... } because namespace MyNS { namespace Private { // ... } } works just fine as-is. Analogously, you can't write class MyNS::MyClass { // ... }; but have to write namespace MyNS { class MyClass { //... }; } -cd --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Randy Maddox Guest Posted: Thu Apr 15, 2004 5:06 am    Post subject: Re: Nested namespaces definition [email]ab4ds (AT) hotmail (DOT) com[/email] ("adeht") wrote in message news:<407c201b$1 (AT) news (DOT) bezeqint.net>... Quote: Why won't the standard allow the following? namespace MyNS::Private { // ... } Perhaps because you can accomplish what you want with: namespace MyNS { namespace Private { } } Then anything in Private is accessed as MyNS::Private::whatever. Randy. --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.jamesd.demon.co.uk/csc/faq.html ] Back to top Steven T. Hatton Guest Posted: Thu Apr 15, 2004 5:09 pm    Post subject: Namespace private context, was Re: Nested namespaces definit adeht wrote: Quote: ""Steven T. Hatton"" <hattons (AT) globalsymmetry (DOT) com> wrote in message news:P4WdnbJgqdLx8-DdRVn-vA (AT) speakeasy (DOT) net... This is something Mathematica supports for its packages. I've wondered the same thing. I haven't proposed this for C++ simply because I had not come across a use for it in C++. How would such a construct benefit the language? I didn't search, sorry about that. Here's the proposal: http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/papers/2003/n1524.htm You can read about the possible uses for that in the paper. I guess I didn't understand what you were suggesting. My response was addressing the "Private" concept suggested by your example. In Mathematica, there is something called a package which functions much like a namespace in C++. One feature is a mechanism to declare a private context within a package. This is analogous to the private declaration mechanism used in C++ classes. More discussion of Mathematica packages can be found here: http://documents.wolfram.com/v5/TheMathematicaBook/PrinciplesOfMathematica/ModularityAndTheNamingOfThings/2.7.10.html This could conceivably be used in C++ to hide namespace local code that is only needed internally to the namespace. As I said, I haven't found a compelling argument for suggesting this for C++, but since your example hinted at such a thing, I thought it would be worth bringing to people's attention. And then there is the obvious 'protected' access specifier which might be used to share implementation details with more deepley nested namespaces. One implementation of this concept might look something like the following: namespace nsA { private: //nsA local accessible namespace nsAPriv { //accessible to nsA only } protected: //accessable to nsA and anything under nsA namespace nsAProt { //accessible to nsA and namespaces under nsA } public: //the same as it is now namespace nsAPub { // can access nsA public and protected but not private // accessible to anything that can access nsA public } } Is it useful? I can't offer a compelling argument for it. The concept, however, seems worth considering. -- STH http://www.kdevelop.org http://www.suse.com http://www.mozilla.org --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. 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