Bill Baxter wrote:
On Tue, Sep 29, 2009 at 8:46 AM, Don <nos...@nospam.com> wrote:
Bill Baxter wrote:
And also, is this statement true?
since C++ programmers tend to "when in doubt, make it virtual"
Do they? (Might be true, but I don't remember ever hearing it anywhere
else).
They might in practice, but the current preaching I hear is to
generally to make the slimmest and least virtual interface you can get
away with. Of course nobody would need to preach about such
methodology if there weren't some contrary trend commonly seen out in
the wild.
Well there are two considerations that are in tension. One is that an
abstract interface should be sufficient for getting work done, and that
pushes its size up. If interfaces are too slim, people tend to "extend"
them on the implementation side and then cast down to implementation
whenever they need to get anything done. That pushes the size of
interfaces upwards.
The other consideration is that interfaces should be narrow such that
they are not difficult to understand and implement.
So thinking of making an interface as small as possible or as
comprehensive as possible may miss part of the tradeoffs involved.
NVI offers the ability to distinguish between the interface that must be
implemented, and the interface that gets used.
Andrei
