Re: [boost] shared_ptr type_info, void cast

From: Peter Dimov (pdimov_at_[hidden])
Date: 2007-05-26 08:38:10

Felipe Magno de Almeida wrote:
> On 5/23/07, Peter Dimov <pdimov_at_[hidden]> wrote:
> 
> 
>> [snip]
> 
>> 
>> struct Base
>> {
>>     virtual ~Base() {}
>> };
>> 
>> struct Derived: Base
>> {
>>     int i;
>> };
>> 
>> Derived * pd = new Derived;
>> Base * pb = pd;
>> shared_ptr<void> pv( pb );
> 
>> [snip]
> 
>> 
>> or
>> 
>>     pv->pointer() == pd && pv->type() == typeid(Derived);
> 
> Sorry if it is too obvious. But how can shared_ptr implement
> pv->pointer() == pd ?

It can use dynamic_cast<void*>( pb ) to obtain pd when *pb is polymorphic.