From: Gavin Collings (gcollings_at_[hidden])
Date: 2000-03-21 12:13:30
"borgerding, mark a." <marka-_at_[hidden]> wrote:
original article:http://www.egroups.com/group/boost/?start=2709
>
> There are a few reasons I shied away from using template friends
> 1) Compiler support for template friends is less than universal.
Avoiding
> them reduces the amount of #ifdef code to maintain.
> 2) I don't like using friends unless they clearly strengthen
encapulation
> (This point is arguable for linked_ptr_base)
> 3) I think it reads better without the template friends. (Personal
> preference perhaps)
There do seem to be arguments in both directions for this type of
thing. I tend to go with Scott Meyers et al and use public inheritance
only to express an is-a relationship. Though I have to confess to
getting a little tired of the using directives that the approach
implies (and have bypassed them on occasion).
Answering your points.
1) Yes it is a pain that template friends aren't universally supported,
but hopefully, it's a temporary situation.
2) The argument for increased encapsulation is exactly that for which
Miki proposed his fix - that of clients getting hold of a
linked_ptr_base pointer. This is highly unlikely in itself, since
linked_ptrs would typically be used by value, so polymorphism wouldn't
enter in to it. But having acknowledged that a problem exists, better
to make more explicit the fact that a linked_ptr should not be used as
a linked_ptr_base IMO.
3) My personal preference leans the other way. Not strongly though, if
you say no, I'll leave it as it is.
Gavin