[geos-devel] More Info - Another Portability Quirk

[Norman Vine]

Paul Ramsey writes:

> I just went through my stl_*.h files, as well as the G++ STL online 
> documentation, and it looks like at() is a recent addition to the G++ 
> STL -- sometime in the 3.x series (mine is from gcc 2.96 vintage). Are 
> there other accessors which are possible, or is a latest-and-greatest 
> STL going to be one of our requirements? Is there a way of having 
> configure check the existance of various components of the STL?

Paul

You can use the [] operator, in fact I made all of the changes
locally todo this then realized that the at() method performs
an out of range check that the [] operator doesn't so didn't
forward my changes.

as you noticed  according to http://gcc.gnu.org/libstdc++/status.html
gcc users will need to use a 3.x version inorder to use libstdc++3

My current thinking is that it is probably worth going with the
newer at() because of the builtin range checking

As a temporary measure I could update my patch so that it
was done with a bunch of 
#if defined(__GNUC__) &&  (__GNUC__ < 3 )
 use []
#else
 use at()
#endif

but this is rather ugly :-(

Another solution would be to use a typedef

#if defined(__GNUC__) &&  (__GNUC__ < 3 )
typedef GEOS_VECTOR geos_vector

template < class _Tp >
class geos_vector < _Tp > : public vector < _Tp >
{
// add at() members
  reference at(size_type __n)
    { return (*this)[__n]; }

  const_reference at(size_type __n) const
    { return (*this)[__n]; }
}
 
#else
 typedef GEOS_VECTOR vector
#endif

and change all occurrences of vector to GEOS_VECTOR

Cheers

Norman