Re: [boost] [pimpl] Mini Review

Subject: Re: [boost] [pimpl] Mini Review
From: Sergiu Dotenco (sergiu.dotenco_at_[hidden])
Date: 2011-05-26 11:37:52

Am 26.05.2011 11:22, schrieb Artyom Beilis:
> The only advantage I can see in boost.pimpl over scoped_ptr or auto_ptr
> is that it does not require explicit destructor.
> 
> i.e.
> 
> 
>    class Foo : boost::noncopyable {
>    public:
>          Foo();
>          int x() const;
>          void x(int v);
>    private:
>          struct data;
>          std::auto_ptr<data> d;
>    };
> 
> No good. You need to add
> 
>   ~Foo();
> 
> So it would know to destroy Foo::Data correctly.

You can't use std::auto_ptr for pimpl implementation in portable code.
Doing so is undefined behavior. To quote ISO/IEC 14882:2003 (§17.4.3.6,
p. 329):

"In particular, the effects are undefined in the following cases:
[...]
— if an incomplete type (3.9) is used as a template argument when
  instantiating a template component, unless specifically allowed
  for that component."

which applies to most standard library types.