Re: [Boost-users] [scoped_array] "optimization"

From: David Daeschler (daveregs_at_[hidden])
Date: 2007-04-25 15:31:57

Hi Michael,

Straight out of the docs
http://www.boost.org/libs/smart_ptr/scoped_array.htm

> Because scoped_array is so simple, in its usual implementation every
> operation is as fast as a built-in array pointer and it has no more
> space overhead that a built-in array pointer.

IMHO saying that the change to an array pointer is an "optimization" at
all is dubious.

-Dave

On Wed, 2007-04-25 at 13:33 -0500, Michael Marcin wrote:
> Hello,
> 
> I have a new programmer on my team who has been brought on as an 
> optimization engineer.  She has a lot more experience than I do but I fear 
> some of that experience may have left impressions that have stuck with her 
> for too long.  On the first check in labeled spot optimizations there were 
> many things changed that disturbed me.  One of them was changing a class 
> from essentially.
> 
> #include <boost/scoped_array.hpp>
> class Context
> {
> public:
>     Context( unsigned int width, unsigned int height )
>         : m_buffer( new unsigned int[width*height] )
>     {
>     }
> 
>     unsigned int* GetBuffer() { return m_buffer.get(); }
> private:
>     boost::scoped_array<unsigned int> m_buffer;
> };
> 
> to
> 
> class Context
> {
> public:
>     Context( unsigned int width, unsigned int height )
>         : m_buffer( new unsigned int[width*height] )
>     {
>     }
>     ~Context()
>     {
>         delete m_buffer;
>     }
> 
>     inline unsigned int* GetBuffer() { return m_buffer; }
> private:
>     unsigned int* m_buffer;
> };
> 
> 
> First of all there is the defect of delete being called instead of delete[]. 
> Other than that I was under the impression that there should be no 
> difference between the two other than the former being more descriptive (it 
> instantly tells me this is an array and the memory is owned by the instance 
> of this class).
> 
> Is this really an optimization?
> 
> Thanks,
> 
> Michael Marcin 
> 
> 
> 
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