On Fri, Apr 19, 2002 at 01:35:10PM -0000, Lars Henrik Mathiesen wrote:
> > Date: Thu, 18 Apr 2002 23:44:26 +0200
> > From: Paul Johnson <[EMAIL PROTECTED]>
> >
> > On Thu, Apr 18, 2002 at 07:56:06PM -0000, Lars Henrik Mathiesen wrote:
> > > I would like to write
> > >
> > > for my $key ( $hash{foo}->keys ) { print $hash{bar}->{$key} }
> >
> > This, or something similar was hashed out on p5p, ooooh, about 4 years
> > ago, give or take four years ;-) Actually, I think it might have been
> > when Chip was Pumpking, which would have made it about five years ago.
>
> I'm not surprised that other people suggested it... and I'm sure that
> there are good arguments against as well.
>
> Hmmm... I just realized that it's possible to get almost the same
> thing by misusing bless:
>
> package hash;
> sub bless { bless shift }
> sub keys { keys %{+shift} }
> sub values { values %{+shift} }
> sub hash { %{+shift} }
>
> package main;
>
> my $href = hash::bless { foo => 1, bar => 2 };
>
> print join ', ', $href->keys;
> print join ', ', $href->values;
> print join ', ', $href->hash;
>
> Tempting --- now if only I could create a method named % or @ ... I'm
> not sure how many optimizations this loses relative to the %{ $href }
> construction, though.
Creating methods with names '%', '@' or whatever isn't the problem.
The problem is calling them.
#!/usr/bin/perl -w
use strict;
package hash;
sub bless { bless shift }
{
no strict 'refs';
*{'hash::@'} = sub {keys %{+shift}};
*{'hash::*'} = sub {values %{+shift}};
*{'hash::%'} = sub {%{+shift}}
}
package main;
my $href = hash::bless { foo => 1, bar => 2 };
$\ = "\n";
$, = ", ";
print $href -> $_ foreach qw /@ * %/;
__END__
Running this gives:
foo, bar
1, 2
foo, 1, bar, 2
But '$href -> %' and also '$href -> "%"' are syntax errors. You
can put a variable on the right side of an arrow, but not a
literal string.
Abigail
