[boost] Re: addition to has_nothrow_destructor

From: Daniel Frey (daniel.frey_at_[hidden])
Date: 2003-10-01 09:58:09

Alexander Nasonov wrote:
> Alexander Nasonov wrote:
> 
>>Hi,
>>I think it's possible to detect classes that have dtor with throw() spec.
>>The trick is based on a fact that implicitly declared dtor inherits
>>throw-spec from its bases and a fact that virtual dtor overrided in a
>>derived class can't have less restrictive throw-spec.
>>
>>In this example, tester<T> can only be instantiated if T's dtor looks like
>>T::~T() throw(); otherwise, a compiler will complain. SFINAE can be
>>applied to get rid of compile error.
>>
>>struct virtual_nothrow_dtor
>>{
>>    virtual ~virtual_nothrow_dtor() throw();
>>};
>>
>>template<class T>
>>struct tester : T, virtual_nothrow_dtor
>>{
>>    // Implicitly defined dtor
>>};
>>
> 
> I'm trying to apply this technique
> http://groups.google.com/groups?q=richard%40ex-parrot.com+type_fwd&hl=en&ie=ISO-8859-1&oe=ISO-8859-1&selm=1011126576.17796.0.nnrp-02.3e31d362%40news.demon.co.uk&rnum=1
> but I can't. Is something wrong there?
> [snip]

SFINAE won't help, as it cannot be applied in your case. If 
instantiation happens, it must succeed - no chance to get around this 
AFAIK. SFINAE only works - as the name already suggests - for 
substitutions, i.e. whether or not a type contains a sub-type.

Regards, Daniel

-- 
Daniel Frey
aixigo AG - financial training, research and technology
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