Re: sgi extensions

[Nathan Myers <ncm-nospam at cantrip dot org>]

On Fri, Nov 22, 2002 at 02:44:13PM -0500, Phil Edwards wrote:
> On Fri, Nov 22, 2002 at 11:42:45AM -0800, Tim Arland wrote:
> > 
> > Are there namespace tricks I need to do to get at the sgi extensions? 
> > simply using #include <ext/hash_map> doesn't seem to be doing the trick 
> > as it claims hash_map is undeclared.
> 
> They're in the __gnu_cxx namespace.

For maximum portability, consider defining a namespace alias to use 
to talk about extensions.  E.g.

  #ifdef __GNUC__
  #if __GNUC__ < 3
    #include <hash_map.h>
    namespace Sgi { using ::hash_map; }; // inherit globals
  #else
    #include <ext/hash_map>
    namespace Sgi = ::__gnu_cxx;
  #endif
  #else // ...  there are other compilers, right?
    namespace Sgi = std;
  #endif

  Sgi::hash_map<int,int> my_map;

This is a bit cleaner than defining typedefs for all the instantiations
you might need.  (It's a pity you can't say "namespace Sgi = ::;".)

Phil, you might suggest something like this in the docs.

Nathan Myers
ncm-nospam@cantrip.org