On Tue, Feb 15, 2005 at 10:58:13AM +0000, Angus Leeming wrote:
> class Mover {...};
> class SpecialisedMover : public Mover {...};
>
> class Movers {
> public:
> /// @c returns the Mover registered for format @c fmt.
> Mover const & operator()(std::string const & fmt) const
> {
> SpecialsMap::const_iterator const it = specials_.find(fmt);
> return (it == specials_.end()) ? default_ : it->second;
> }
>
> private:
> typedef std::map<std::string, SpecialisedMover> SpecialsMap;
> SpecialsMap specials_;
> Mover default_;
> };
>
> MSVC warns that Movers::operator() is "returning address of local variable
> or temporary". I guess that the code is indeed unsafe if it->second is a
> copy of the data in the store.
>
> Should I change the function signature?
I am not sure the message is valid. Sure, the compiler sees a tmporary
and returning a reference to a part of something refered to by the
temporary. However, that thing is not a temporary but lives in a
structure outside. The compiler does not know, but we do. So my
guess is the code is safe and the warning is bogus.
Andre'
