Re: How to make this exception-safe
On Nov 19, 3:40 pm, Brendan <catph...@catphive.net> wrote:
std::vector<std::auto_ptr<C>> v_;
Using an auto_ptr as the template argument to a vector is dangerous
for other reasons (stl algorithms that expect copy semantics may be
unsafe), but it should be correct for at least the code you presented.
V had an implicit copy ctor, which ipso facto woould make the code
unsafe.
Aside from being verboten by the standard, there are problems of
portability (IIRC the standard requires that
std::container<std::auto_ptr<T> > not even compile. Most however allow
it.)
a safer version of std::vector<auto_ptr<C> > is this
V::V:_v(3){
_v[0].reset(new C(1));
_v[1].reset(new C(3));
_v[2].reset(new C(2));
}
And then make sure that
1. _v is never grown (because that forces an internal copy
2. _v is never copied
3. _v iterators are never accessed
4. that you never do something like
std::vector<std::auto_ptr<C>>::value_type tmp=v.at(0);
so on and so forth.
The best answer I think would be to use boost::intrusive_ptr for this
case. It overcomes most of the objections that people have with
shared_ptr
Lance
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