Tony Olekshy wrote:
> There you have it. That's why RFC 88 uses structured data for $@.
That's a good argument, one that I have no quarrel with. As an
enhancement to eval/die, this would make it more flexible for checking
conditions. And with appropriate stringification, it is upward
compatible with the current uses of $@ by eval/die.
Transliterating $@ to whatever would be used equivalently for an
exception mechanism, I still agree that structured data is good.
> Now, here's an alternative that may keep everyone happy. In
> addition to whatever RFC 88 does now, change this rule about how
> die behaves:
>
> If passed a single argument that isa "Exception", raise it as
> the new exception and die in the fashion that Perl 5 does.
>
> Otherwise, the arguments are stringified and joined with C<''>
> (as in Perl 5), the resulting string is wrapped up in a new
> Exception object (setting the message instance variable to said
> string), and the new Exception object is raised.
>
> to read like this:
>
> If passed a single argument that isa "Exception", raise it as
> the new exception and die in the fashion that Perl 5 does.
>
> Otherwise, the arguments are stringified and joined with C<''>
> (as in Perl 5), the resulting string is wrapped up in a new
> Exception object (setting the message instance variable to said
> string), the original unstringified arguments are saved in a
> list ref in the object's C<args> instance variable, and the new
> Exception object is raised.
>
> then you can say C<die qw(A B C)>, and the following tests both work:
>
> catch $@->args->[1] eq "B" => { ... }
>
> catch $@ =~ /B/ => { ... }
>
> Yours, &c, Tony Olekshy
We're getting closer and closer. Now we just need a magic array such
that before the first catch clause is executed, it gets assigned the
contents of @{$@->args}. I guess (per your other postings), that could
be achieved via RFC 88 functionality by:
try on_catch_enter => sub { @! = @{$@->args}; return true; },
{ ...
}
catch $![0] == 53 => { ... };
On the other hand, that would conflict with your use of on_catch_enter
for other purposes, but I use it to demonstrate the functionality I'd
like to see: that catch can directly access the list of arguments passed
to throw, whatever they are. I'm not sure I fully understand the way the
on_catch_enter hook works or is set, and I don't want to have to actually
do this to achieve the goal.
--
Glenn
=====
There are two kinds of people, those
who finish what they start, and so
on... -- Robert Byrne
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