Re: 'academic' problem ( speed/memory efficiency vs. human readability and

From:

"Andrei Alexandrescu (See Website For Email)" <SeeWebsiteForEmail@erdani.org>

Newsgroups:

comp.lang.c++.moderated

Date:

31 Jul 2006 08:09:29 -0400

Message-ID:

<44CD751C.7060004@erdani.org>

Dave Harris wrote:

SeeWebsiteForEmail@erdani.org (Andrei Alexandrescu (See Website For
Email)) wrote (abridged):

Earl Purple wrote:

Optimal (won't create a temporary then copy it) at the cost of
showing the user the implementation.

I'm not sure I understand. Aren't value parameters all but
indistinguishable from const reference parameters? What does the caller
care?

I'm not Earl Purple, but when I've played around with this approach I
found it did leak implementation. If you switch between copy and
const-reference depending on whether the function body needs to make a
copy, you'll find that functions that conceptually should have the same
interface in fact do not. This shows up with virtual functions. A function
that makes a copy won't override one which doesn't make a copy.

This is a valid point. I openly admit that my analysis didn't take
overriding into account; I've considered it implicitly a different kin.
As often those functions are implementation-free (start as pure
virtuals), implementation decisions to them is not applicable.

Andrei

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