Question

I have a template class (Node is an inner class within a BST). It’s now time to free up the memory; Given that either the key or the value (or both) may be pointers, I must figure out how to free them if they are.

See an example:

~Node( void )
{
    if ( is_pointer< TValue >( Value ) )
    {
         delete Value;
         Value = NULL;
    }

    if ( is_pointer< TComparable >( Key ) )
    {
         delete Key;
         Key= NULL;
    }
}

The implementation behind the is_pointer< T > function works (Taken from here), however as soon as I press delete on either Key or Value, I get the following:

Error   13  error C2440: 'delete' : cannot convert from 'esc::Shader' to 'void *'   c:\programming\c++\git\escalator\engine\engine\searchtree.hpp   131
Error   14  error C2440: 'delete' : cannot convert from 'esc::ShaderComparable' to 'void *' c:\programming\c++\git\escalator\engine\engine\searchtree.hpp   137
Error   12  error C2679: binary '=' : no operator found which takes a right-hand operand of type 'int' (or there is no acceptable conversion)   c:\programming\c++\git\escalator\engine\engine\searchtree.hpp   130

I’ve tried static_cast, dynamic_cast, reinterpret_cast, etc, but neither of these appear to work.

What’s a good solution?

Answer 1

I must figure out how to free them if they are.

Don’t. Really- don’t. That’s the user’s problem- and he can supply a smart pointer if he wants this behaviour. After all, what if I want to map non-owning pointers? Or need a custom deleter?

Also, your code does not work because you compile the dead code if branches anyway, because you did not use a specialization.