[Boost-users] Request help with boost::compose to boost::bind conversion

From: gdprosch_at_[hidden]
Date: 2006-01-30 18:35:40

Let me apologize in advance for my ignorance but I have not been able to
update the following code successfully in order to migrate from Boost
1_29 to 1_33.  Despite reading the boost::bind documentation a few times
I am failing to make the necessary connection regarding the use of _1,
_2 and handling the use of DeRef in the equal function below.

// Unary dereference functor (a functor that returns the value of the
specified
// parameter, dereferenced via operator*)
// (Note: This DeRef code is included in a separate header.)
template < class Ptr, class T >
struct DeRef
  : public std::unary_function< Ptr, T >
{
  T & operator()( Ptr & ptr ) const
  { return *ptr;}
};

// ---

// Compare LocalStringMap (a custom map container with Tag/Value pair).
// A TagValue is a class that contains a tag and a value (both strings)
// A TagValuePtr is a custom, dereferencable smart pointer. 
inline bool LocalStringMap::operator==( const LocalStringMap &that )
const
{
  // Must be same size
  if( this->size() != that.size() ) { return false;}

  return
    equal( this->_list.begin(),
           this->_list.end(),
           that._list.begin(),
           boost::compose_f_gx_hy( equal_to< TagValue >(),
                            DeRef< const TagValuePtr, const TagValue
>(),
                            DeRef< const TagValuePtr, const TagValue >()
) );
}

Any assistance with this would be most helpful.  I get the impression
that I do not need to use the DeRef class the original author created
given boost:bind's more capable traits identification.  Here's what I
have so far...

  return
    std::equal( this->_list.begin(),
                this->_list.end(),
                that._list.begin(),
                boost::bind<bool>( std::equal_to< TagValue >(),
                   ???

Thank you,

Greg Prosch
Micron Technology, Inc.