[Halld-offline] [Fwd: Re: [Halld-online] Boost shared_ptr for Hall D Online]

[Elliott Wolin]

 From Graham Heyes, who was unable to post to the offline mail list:



-------- Original Message --------
Subject: 	Re: [Halld-online] Boost shared_ptr for Hall D Online
Date: 	Mon, 21 Dec 2009 10:31:43 -0500
From: 	Graham Heyes <heyes at jlab.org>
To: 	Elliott Wolin <wolin at jlab.org>
CC: 	halld-online at jlab.org, halld-offline at jlab.org
References: 	<4B2F9257.1090708 at jlab.org>



This is nice in principle but can you guarantee that you will run Linux, and in particular 
that the Boost shared pointer will be there, for the lifetime of GLUEX and hall-D? We are 
still five years or so from taking data in large volumes and I would hope that hall-D will
 be around for a few years after that. I know that CODA uses some third party libraries etc 
but Boost is a Linux only deal right now.

My 10c worth,
		Graham


On Dec 21, 2009, at 10:20 AM, Elliott Wolin wrote:

> Hi,
> 
> The Boost shared pointer (a type of smart pointer) appears now to be 
> standard on linux (I found it on my 32-bit and on my 64-bit RHEL 
> machines).  I think we should seriously consider using it for the Hall D 
> online.  See:
> 
>    http://www.boost.org/doc/libs/1_41_0/libs/smart_ptr/shared_ptr.htm
> 
> for details. 
> 
> My proposal would be to outlaw "bare" pointers for all but the most 
> trivial tasks (and for backwards-compatibility in some cases), and use 
> the shared_ptr extensively.  At some point I or someone else will give a 
> report on this at the Online meeting.  This is not an urgent decision, 
> of course.
> 
> Briefly, the shared_ptr class wraps a standard pointer in such a way as 
> to eliminate memory leaks.  It keeps a reference count of the number of 
> places the wrapped ptr is being used, and guarantees that delete() is 
> called when it is not being used any more (very similar to what is done 
> in Java). 
> 
> The Online is fortunate that no real code has been developed yet and we 
> can adopt the shared_ptr before we start.  I think it would be a great 
> idea for the offline to use it as well, but they 1) must support other 
> architectures where it may not be standard yet, and 2) already have a 
> large base of code.
> 
> Thanks,
> 
> -- 
> 
> 				Sincerely,
> 					Elliott
> 
> 
> ================================================================================
> 
> 
> Those raised in a morally relative or neutral environment will hold
> 		    no truths to be self-evident.
> 				   
> 
> Elliott Wolin
> Staff Physicist, Jefferson Lab
> 12000 Jefferson Ave
> Suite 8 MS 12A1
> Newport News, VA 23606
> 757-269-7365
> 
> ================================================================================
> 
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-- 

				Sincerely,
					Elliott
 

================================================================================


 Those raised in a morally relative or neutral environment will hold
		    no truths to be self-evident.
				   

Elliott Wolin
Staff Physicist, Jefferson Lab
12000 Jefferson Ave
Suite 8 MS 12A1
Newport News, VA 23606
757-269-7365

================================================================================