Re: [boost] [Review] Shmem

From: Ion Gaztañaga (igaztanaga_at_[hidden])
Date: 2006-02-08 00:59:35

Hi Jeff,

> I think he's pointing out the lack of RAII. From your first example:
> 
> 
>   named_shared_object segment;
> 
>    if(!segment.create("/MySharedMemory",  //segment name
>                      65536)){            //segment size in bytes
>       return -1;
>    }
> 
>    void * shptr   = segment.allocate(1024/*bytes to allocate*/);
> 
>    segment.deallocate(shptr);
> 
> I'd rather see:
> 
>   try
>   {
>      named_shared_object segment("/MySharedMemory",65536);
> 
>      shmem::shared_ptr lPtr = segment.allocate(1024);
>   }
>   catch( const shmem::exception& aExc )
>   {
>     ...
>   }

I see. Anyway, in the first example, if "allocate" throws, segment 
destructor will automatically unmap and destroy the segment. If you 
think that a one step constructor is better, there is no problem to add 
it. Just like fstream can do a default constructor or open the file in 
the constructor.

The only minor point is that we have to say if we want to create, 
connect or open_or_create the segment in the constructor, so we need an 
extra constructor.

> Which brings up the issue that I could not easily find any discussion of 
> lifetime requirements in the documentation.

Ok. It's true that the segment must be open while using it but, maybe I 
should point out with some lifetime examples.

Thanks,

Ion