On Thu, Oct 03, 2002 at 02:29:57PM -0700, Michael Lazzaro wrote:
> One question I still have is the syntax of pre/post conditions, e.g:
>
> > method turn($direction, $how_sharp) {
> > pre { $how_sharp <= 20 } is private;
> > ...implementation...
> > }
>
> This is obviously how it would fall out from Apocalypse 4, "pre/post"
> being basically types of exception, but I keep having nagging concerns
> about it. To me, this keeps looking like "pre { ... }" is a
> precondition attached to the _implementation_ of the given method, not
> the _signature_ of a given method...
I don't know, but I think it's supposed to be like this:
# part of the signature
method turn($dir,$ang) is pre { $ang <= 20 } {
...
}
# part of the implementation
method turn($dir,$ang) {
PRE { $ang <= 20 }
...
}
turn() methods of derived classes would inherit the precondition in the
first case but not the second. I don't know why you'd want to do this
exactly, but it seems to me that perl should allow it.
> On Thursday, October 3, 2002, at 01:11 PM, Allison Randal wrote:
> > BTW, that's:
> > attr $.tilt;
> > Attributes are private by default.
>
> (As a lame aside, are we going to have a concept of "private" vs.
> "protected" vs. "public", or just private/public? (In other words,
> does "private" permit access by subclasses?) Not recommending it, just
> wondering if anyone thinks we need it.)
I don't think we should be actively reproducing C++'s mistakes :-)
With the constructs shown so far, I can guess that it should be
possible for someone to implement "protected" if they wanted it.
-Scott
--
Jonathan Scott Duff
[EMAIL PROTECTED]
