From -3393620476734395369 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 109fba,22e67e794d61e771 X-Google-Attributes: gid109fba,public X-Google-Thread: f78e5,22e67e794d61e771 X-Google-Attributes: gidf78e5,public From: clamage@eng.sun.com (Steve Clamage) Subject: Re: The definition of namespace. Date: 1999/09/01 Message-ID: <7qjhvn$43r$1@engnews1.eng.sun.com>#1/1 X-Deja-AN: 519797356 X-NNTP-Posting-Host: taumet.eng.sun.com Approved: stephen.clamage@sun.com (comp.std.c++) References: <37cbef06.0@newsfeed.jdedwards.com> X-UID: 0000000001 X-Status: $$$T Organization: Sun Microsystems Inc., Mountain View, CA Newsgroups: comp.lang.c++,comp.std.c++ Originator: clamage@taumet "Jerry" writes: > I feel that the namespace and scope are almost the same thing. So I give >the definition of namespace as the name of a scope. Is it a correct >definition? Thanks in advacne. A namespace defines a scope, but not all scopes have all the properties of namespaces. Unlike other scopes, a namespace can be reopened and added to. Names from namespaces can be imported selectively or accessed en masse in other scopes. You can do that to a limited extent with class scopes, but not at all with other kinds of scopes. In addition, not all namespaces have names. The global namespace has no name (it's considered a namespace to make other parts of the language definition easier to specify). You can declare unnamed namespaces. An unnamed namespace has a name, but you cannot write it. Finally, there are other kinds of scopes that are unlike namespaces. To pick one example, a block scope in a function can contain statements directly; a namespace cannot. So, yes, except for the quirks of the global namespace and unnnamed namespaces, a namespace names a scope. But "namespace" and "scope" are not the same thing. Namespaces were introduced into C++ because the existing scope rules were deemed inadequate to handle large (or even medium-large) programs. -- Steve Clamage, stephen.clamage@sun.com [ 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://reality.sgi.com/austern_mti/std-c++/faq.html ]