[boost] Re: Sorting list < shared_ptr < foo > > usingstd::list::sort()

[Daniel Frey]

HEATH DAVIS wrote:
I have experienced some difficulty with sorting lists of type:

list < shared_ptr < foo > >

> [snip]
>
bool my_class::operator<(const my_class& arg)
{
return m_val < arg.m_val;
}
> [snip]
//sort the list
my_list.sort();
Here, you basically sort by using

shared_ptr::operator<

instead of

my_class::operator<

You need something like

template< T > struct shared_ptr_content_less
{
  bool operator()( const boost::shared_ptr< T >& lhs,
                   const boost::shared_ptr< T >& rhs ) const
  {
    return *lhs < *rhs;
  }
};
and call

my_list.sort( shared_ptr_content_less< my_list >() );

The code is untested, but I hope you get the idea. Also, there might be 
some easier way using other boost-libs to create the helper on-the-fly, 
but others definitely know better than me :)

Regards, Daniel

--
Daniel Frey
aixigo AG - financial training, research and technology
Schloß-Rahe-Straße 15, 52072 Aachen, Germany
fon: +49 (0)241 936737-42, fax: +49 (0)241 936737-99
eMail: [EMAIL PROTECTED], web: http://www.aixigo.de
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