Re: Interfaces and non-virtual destructors
Marcel M?ller wrote:
If i have an interface like
template <class K>
struct IComparableTo
{ virtual int compareTo(const K& key) const = 0;
};
some compilers (e.g. gcc) warn me about that the class has virtual
functions but a non-virtual destructor. While this can be helpful in
some cases, it can be annoying too.
If the interface is a template like in the example I get hundreds of
warnings for each type instantiation in each compilation unit.
From the applications point of view it might be not reasonable to
delete the entire object through a particular interface. In such cases I
usually write
template <class K>
struct IComparableTo
{ virtual int compareTo(const K& key) const = 0;
protected:
~ICompareableTo() {}
};
to avoid accidental deletion. But the warnings still hide other, more
important messages.
Is there another way to declare interfaces?
Yes, with the class keyword :-) No, just kidding, of course... there's
no problem in your code. What version of gcc are you using? I have up
to 4.1.1 (built yesterday -hurrah!), and it still emits the warning.
*Perhaps* they fixed that in 4.2 or 4.3 (when the destructor is
protected and the class declares no friends). It's a long-standing
annoyance.
(Off-hand, I think it would require a trivial change in cp/class.c; I
have no idea why they haven't fixed it yet)
--
Gennaro Prota | name.surname yahoo.com
Breeze C++ (preview): <https://sourceforge.net/projects/breeze/>
Do you need expertise in C++? I'm available.
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