On Thu, 20 May 2010 06:34:42 -0400, Steven Schveighoffer
<schvei...@yahoo.com> wrote:
Robert Jacques Wrote:
On Wed, 19 May 2010 21:42:35 -0400, Steven Schveighoffer
>
> Does that make sense?
>
> -Steve
Yes and No. I understand where your coming from, but I think it's a bad
idea. First, I think it needlessly expands the radius of comprehension
needed to understand and use the library. (See Tangled up in tools
http://www.pragprog.com/magazines/2010-04/tangled-up-in-tools) Second, I
think designing a library to be flexible enough to meet some future,
anticipated need (e.g. dlls) is a good idea, but actually implementing
vaporous future needs is fraught with peril; it's too easy to guess
wrong.
Third, interface base design is viral; If library X uses interfaces
then I
have to use interfaces to interface with it. And if another library Y
uses
classes, then I'm going have to write a (needless) wrapper around one of
them.
I understand these points, but I'm already using interfaces to copy data
between containers. I don't have to, I could have used generic code,
but this way, only one function is instantiated to copy data from all
the other containers. The problem with using generic code is that the
compiler will needlessly duplicate functions that are identical.
This sounds like a failure of design. Why aren't you using ranges to do
this?
Using interfaces is not as viral as you think. My interfaces can be
used in generic code, as long as the generic code uses functions in the
interfaces. If a library returns an interface, the author is saying "I
don't want you using any functions outside this interface," so why is
that a bad thing?
Well, needlessly duplicated functions for one. :) More importantly, the
example I gave was about third party libraries which I have no control
over. So this solution explicitly doesn't work. And even if everyone used
templates everywhere in order to be compatible with both interfaces and
classes, isn't that a viral effect of having both?
Forcing people to *not* use interfaces has its drawbacks too.
Dcollections gives the most flexible design I could muster, while still
being useful.
I'm not saying I'm against removing the interfaces until some later
date, but I don't see any convincing arguments yet, especially since
I've already seen benefits from having them.
-Steve
