Re: Searching a motivating example for upcasts

From:

Tom Anderson <twic@urchin.earth.li>

Newsgroups:

comp.lang.java.programmer

Date:

Sat, 18 Dec 2010 21:23:15 +0000

Message-ID:

<alpine.DEB.1.10.1012182120510.24010@urchin.earth.li>

On Sat, 18 Dec 2010, Andreas Leitgeb wrote:

Stefan Ram <ram@zedat.fu-berlin.de> wrote:

    .---------------------------------------------------------.
    | So I am looking for any real world examples where it is |
    | advantageous to limit voluntarily the possibilities of |
    | some object in order to make sure that one uses a |
    | general procedure on it. |
    '---------------------------------------------------------'

If your point is specifically about local variables, as in the pattern
Map<X,Y> map = new HashMap<X,Y>();
then I'll step back, as for me, saving 4 key strokes (even 5 when
counting the Shift-key) would be enough, and about all the reason
to do so.

That would actually be a very good example. It's simple, but it's
realistic, common, and it brings home this point about programming to
interfaces rather than implementations, which really means programming to
the most abstract type that supports the necessary operations.

tom

--
fuck = the new period -- jsolo_uno