From: Bo Persson (bop_at_[hidden])
Date: 2007-05-05 06:17:51
Jonathan Franklin wrote:
:: On 5/4/07, David Abrahams <dave_at_[hidden]> wrote:
:::
:::
::: For example, GCC has a
::: warning about a derived class whose base doesn't have a virtual
::: dtor. It's actually *impossible* (not just inefficient or
::: convoluted) to implement is_polymorphic without generating that
::: warning.
::
::
:: Interesting. I'm obviously flaunting my ignorance, but I didn't
:: realize
:: that inheriting from a class sans virtual dtor was ever a Good
:: Thing. I'll have to read up on the issues WRT is_polymorphic.
::
Here's an example from the standard library:
template<class _Ty>
struct plus
: public binary_function<_Ty, _Ty, _Ty>
{ // functor for operator+
_Ty operator()(const _Ty& _Left, const _Ty& _Right) const
{ // apply operator+ to operands
return (_Left + _Right);
}
};
Neither plus nor binary_function has any virtual destructor, but they are
still useful.
You will not use them polymorphically though.
Bo Persson