On 05/20/2010 05:34 AM, Steven Schveighoffer 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.
There is a copy() function that copies any range to any other range. It
might need a revisit, but I think the way to go about copying is generic.
Let's not forget that the code for copying itself is rather short and
that applications don't tend to use a large number of container types.
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?
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.
What are the benefits that you have noticed? I think you'd need to back
up the copying argument with some data if you want to frame it as a benefit.
Andrei
