On Tue, Sep 03, 2002 at 04:04:13PM -0400, [EMAIL PROTECTED] wrote:
> Looks pretty groovy to me too. It looks like the .=
> operator, no longer being employed as a string appender,
> now means "use the class I just mentioned".
Er, not quite. It's just like the other X= operators:
$a = $a + 1 -> $a += 1
$a = $a.new(...) -> $a .= new(...)
So, in the date example:
my Date $date .= new('Sep 21, 1963');
it calls $date.new() and since $date is a Date we get Date.new()
(at least that's how I understand things)
But what happens when someone accidently does this:
my Dog $spot .= Greyhound.new('Lightning');
Somehow I think this will be a common error if this syntax is adopted
(though, in truth, I like it MUCH better than the alternatives I've
seen so far). I'd expect Perl to complain loudly if someone does the
above, but other people may have other ideas.
> If so, perhaps it would only be a small step further for
> it to also mean "and if I don't give the name of the method,
> use new_from_[class of object being passed]". So, the following code
> would call Date::new_from_String, passing 'Sep 21, 1963' as the
> sole argument:
>
> my Date $date;
> $date .= 'Sep 21, 1963';
I too thought of this only it looked more like
my Date $date .= 'Sep 21, 1963'; # swell foop
and then I thought things like:
What happens if there is no constructor?
How does it know which constructor to call?
The first question is easily answered by "Perl throws an
exception/error". The second question is more of a general question
about method resolution. I don't recall if it's been decided that there
will be a One True Constructor name (somehow I doubt it), or exactly how
you tag methods as being constructors, but if you can do this:
sub wilma is ctor (str $s) { ... }
sub betty is ctor (str $s) { ... }
then how does Perl know which constructor to call? Or would declaring
two constuctors like that cause Perl to carp at you? (I can't think
of a case where someone would want to have two constructors like that,
but I'm not letting my lack of imagination hinder this discussion :-)
Anyway, I think the method name should be required.
-Scott
--
Jonathan Scott Duff
[EMAIL PROTECTED]
