Re: Review: Base from Member

From: williamkempf_at_[hidden]
Date: 2001-08-07 09:54:19

--- In boost_at_y..., "Ed Brey" <edbrey_at_y...> wrote:
> From: "Douglas Gregor" <gregod_at_c...>
> 
> > > problem of the obfuscation that the hand-coded extra class 
causes:
> it
> > > appears that there is a an is-implemented-in-terms-of relation,
> which
> > > isn't really the intent.  Base_from_member makes the intent 
clear,
> which
> > > is just to work around an initialization ordering limitation.
> >
> > If a generic class can be named to make the intent clear, so can a
> hand-coded
> > one. The hand-coded version also has several advantages:
> > - The fact that the idiom is used at all is confined to the base 
class
> list
> > and the constructors
> 
> Good point.  The naming advantage is small.  There is still utility 
in
> having a standard name, so a reader unfamiliar with the pattern can
> cross-reference the name and look up pre-written documentation on 
what
> is being accomplished.  There is no easy way to accomplish this 
with a
> hand-coded class.  I consider this a small advantage only.  And on 
the
> other hand, since this situation is somewhat rare, an advanced 
reader
> may not be familiar with the boost class, and looking it up may take
> longer than figuring out the hand-written code.

This is a design pattern, and as such the pattern should have a name, 
but there's no reason a base class (or other reusable framework) need 
exist for the pattern.  Everyone knows what a singleton is (and we 
can look up all the details of the pattern), for instance, but most 
of us would agree that it's problematic and not worth the effort to 
create a base class for this pattern.  I'm not sure that the "Base 
from Member" falls in the same category as singleton... it may be 
worth having a reusable framework for implementing this.  I'm just 
pointing out that Patterns already deal with the whole discussion 
above and may be all that's wanted here.  In other words, instead of 
a base class, maybe all that you need is for Boost to start housing 
peer reviewed pattern descriptions.

Bill Kempf