Damian Conway wrote:
>
> Branden wrote:
>
> > Then, what you proposed in RFC 93 through
> >
> > sub { ... } =~ m/.../;
> >
> > could be handled by
> >
> > my $mymatch = MyClassForMatchingFromFileHandles->new($myhandle);
> > $mymatch =~ m/.../;
>
> This is an interesting alternative. The main problem is that matching
> against a blessed object already has a useful meaning in Perl: stringify
> the object (calling its overloaded stringification operator if possible)
> and match against the resulting string.
That may not be a problem. In the absence of overloading of =~, the
object can be stringified (like now) but if =~ is overloaded then that
could take precedence. Or, just make =~ behave the same as eq and use
fallback to get the current stringifying behaviour.
The biggest problem is making =~ overloadable in the first place. This
has a lot of potential but needn't replace your RFC:
use overload "=~" => sub {
my ($obj, $pat) = @_;
my $coderef = $obj->{attr};
$coderef =~ /$pat/;
};
> My other problem with this approach is that it's relatively heavy. Let's
> take the example in the RFC and implement it both ways:
>
> # As the RFC proposes:
>
> sub from_STDIN {
> $_[1] ? $fh->pushback($_[0]) : $fh->getn($_[0])
> }
>
> \&from_STDIN =~ /pat/;
>
> # As Branden proposes:
>
> package From_STDIN;
>
> sub new { bless $_[1], $_[0] }
>
> sub MORE_DATA { $_[0]->getn($_[1]) }
> sub ON_FAIL { $_[0]->pushback($_[1]) }
>
> use overload "=~" => 1;
>
> package main;
>
> From_STDIN->new($fh) =~ /pat/;
>
> Hmmmm. Potentially more flexible, but also much more ponderous.
I wouldn't say *much* more. There is slightly more to do for a module
author (in object setup) but for the module user it is the difference
between:
my $scalar = From_STDIN->new($fh);
$scalar =~ /pat/;
and
my $scalar = From_STDIN_closure($fh);
$scalar =~ /pat/;
The overload technique can be made considerably less ponderous by
creating one class that behaves as your proposal. Then those that like
it could just
use RFC93 sub {
$_[1] ? $fh->pushback($_[0]) : $fh->getn($_[0])
};
my $scalar = RFC93->new;
$scalar =~ /pat/;
--
Rick Delaney
[EMAIL PROTECTED]
