Re: [boost] Re: Proposals: p2m offsets, prebuild<>, squad_ptr<>(ofcourse)

From: Beman Dawes (bdawes_at_[hidden])
Date: 2002-09-01 19:52:45

In reading some old messages originally skipped for lack of time, I came 
across this:

At 03:16 PM 7/23/2002, Philippe A. Bouchard wrote:

 >... policy-based smart pointers (what are they anyways?)?

David Held gave a polite response:

 > Read Modern C++ Design, by Andrei Alexandrescu. ;)

Let me answer a little more bluntly so there is no chance of 
misunderstanding:

Andrei Alexandrescu, Modern C++ Design, Addison-Wesley, 2001, expands the 
idea of traits class into a powerful technique he calls "Policy-Based Class 
Design."  A particularly interesting example he gives is the Loki SmartPtr 
class.

Anyone who discusses smart pointers without being familiar with the policy 
based smart pointer described in Andrei's book runs several risks:

*  They may not be taken very seriously by others.

*  They may reinvent the wheel, only to discover that Andrei invented it 
better.

*  They may fail to reinvent the wheel, thus depriving themselves of a 
possible better solution to their problem.

Greg Colvin's original shared_ptr design, as later extended by Greg and 
Peter Dimov, with help from Darin Adler and other Boosters, has proved to 
be far more versatile than anyone could have imagined when it was first 
proposed ten years ago, particularly when teamed with the other Boost smart 
pointers.  But policy-based smart pointers may be a better choice for those 
who feel they absolutely must have 100% control over every detail of 
implementation.

--Beman