Subj : Templates and overloaded methods
To   : borland.public.cpp.borlandcpp
From : Malcolm Smith
Date : Sat Sep 18 2004 10:41 pm

Hi,

I have this functor:

  struct DeleteIterObject
  {
    template< typename T >
    void operator()(const T* ptr) const
    {
    delete ptr;
    ptr = NULL;
    }
 };


Currently, the code is used like this:

    FOwnerPolicy.DeleteObjects(FContainer.begin(), FContainer.end());

 where FOwnerPolicy is a policy class of type 'TOwnIteratorObjectsPolicy',
shown below:

  struct TOwnIteratorObjectsPolicy
  {
    template< class IterType >
    void DeleteObjects(IterType IterB, IterType IterE)
    {
    std::for_each(IterB, IterE, DeleteIterObject());
    }
  };


Now I'm trying to work out how to specialize DeleteIterObject for the case
when 'T' is a std::pair< U*, V* >.  I've created another functor that will
bind to either the first or the second element and delete the object - like
this for example:

  struct TOwnPairSecondObjectsPolicy
  {
    template< class IterType >
    void DeleteObjects(IterType IterB, IterType IterE)
    {
    std::for_each(IterB, IterE, BindPairSecond(DeleteIterObject()));
    }
  };

[ BindPairSecond is similar in design to Bind2nd, where I pass the .second
element to DeleteIterObject for processing ]

But I cannot work out how to create a specialized case of
DeleteIterObjects().  I would ideally like to convert this:

    std::for_each(IterB, IterE, BindPairFirst(DeleteIterObject()));
    std::for_each(IterB, IterE, BindPairSecond(DeleteIterObject()));

into a single call such as:

    std::for_each(IterB, IterE, DeleteIterObject());

I'm sure it can be done by overloading the operator() method of
'DeleteIterObject' but I cannot work out the syntax.  Is what I'm after
possible ?

-- 
---
Malcolm Smith
MJ Freelancing
http://www.mjfreelancing.com
Borland Technology Partner

.