Re: [boost] A new way of sorting and searching

From: Peter Dimov (pdimov_at_[hidden])
Date: 2004-06-27 08:32:22

Nic Roets wrote:
> Often when I write searching or sorting code in C or C++, I'm
> frustrated that I have to make a new "callback type" compare function.
> E.g. when you want to sort a number of points in 2D space according to
> their distance from a reference point, it's tempting to do something
> like
> 
> struct Pt {
>   int x, y;
> };
> 
> static Pt center; // Global or static variable yuck.
> 
> int PtDistToCenterCmp (Pt &a, Pt &b)
> {
>   return Dist (a, center) - Dist (b, center);
> }
> 
> main()
> {
>   ...
>   center.x = ...;
>   center.y = ...;
>   ...
>   sort (...);
>   ...
> }
> 
> This type of solution has many problems.

int PtDistToCenterCmp( Pt const & a, Pt const & b, Pt const & center )
{
    return Dist (a, center) - Dist (b, center);
}

int main()
{
    sort( first, last, boost::bind( PtDistToCenterCmp, _1, _2, center ) );
}