[Boost-users] Re: why doesn't scoped_ptr have a custom deleter?

From: Pablo Aguilar (pablo.aguilar_at_[hidden])
Date: 2005-01-04 16:53:11

Thanks

"Peter Dimov" <pdimov_at_[hidden]> wrote in message 
news:006301c4f25f$2b9fe2d0$6401a8c0_at_pdimov2...
> Pablo Aguilar wrote:
>> Hi,
>>
>> I'm currently playing around with Apache's Xerces XML library, and
>> found myself needing to ->release some pointers. shared_ptr + mem_fn
>> works great:
>> shared_ptr<DOMBuilder> db(
>>     impl->createBuilder()
>>   , mem_fn(&DOMBuilder::release)
>> );
>>
>> But for the objects I'm using, I don't need a shared_ptr, but just a
>> scoped_ptr. So I'm wondering about the rationale behind not giving
>> scoped_ptr a custom deleter? Is it that shared_ptr's overhead is
>> negligible (when not being shared I mean)?
>
> No, it's that the overhead of a custom deleter (with state) is negligible 
> in shared_ptr's case, but significant in scoped_ptr's case. You'd 
> typically like to return this pointer from a factory function to avoid 
> repeating the deleter part everywhere, too. scoped_ptr can't be returned.