Re: [boost] offset_cast proposal

From: David Abrahams (dave_at_[hidden])
Date: 2002-11-24 08:29:29

Pavol Droba <droba_at_[hidden]> writes:

> Hi,
>
> I have developed a simple cast function which I found very useful. Here it is:
>
> 	template< typename T >
> 	inline T offset_cast( void* p, unsigned int  offset=0 )
> 	{
> 		return reinterpret_cast< T >( static_cast<unsigned char*>( p )+offset ); 
> 	}
> 	
> 	template< typename T >
> 	inline T offset_cast( const void* p, unsigned int offset=0 )
> 	{
> 		return reinterpret_cast< T >( static_cast<const unsigned char*>( p )+offset ); 
> 	}
>
> Its purposes is to simplify a mapping of C-like structure onto binary data. Here is 
> the example: Assume thath you have a network packet in raw format, and you want
> to read IP-header information. You could do following:
>
> 	ip_header* ip=offset_cast<ip_header>( packet, ip_header_offset );
>
> instead of ugly pointer arithmetic.
>
> Is there any interest for something like this in Boost?

My answer: "not if it uses reinterpret_cast, since that's not
portable".

-- 
                       David Abrahams
   dave_at_[hidden] * http://www.boost-consulting.com
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