Jeff,
I have sussed it. Page 353 of the Camel book says of the += operator "the
result is assigned to the left hand operand..."
The result of the '+ 1' method call is that a number in $self is modified.
The last line of the method is:
$self->{_time_offset} = $offset;
...which is fine until the return from that method is assigned with +=
(this assigns $offset to whatever).
So I added:
return $self;
in the function and bingo, it works as expected!
Perl did the right thing. I just didn't realise it.
A trap for new players( like me ): Watch what your methods return when
using assignment operators.
Duh!
Thanks for your help.
Richard
At 10:47 3/06/2001 -0400, Jeff Pinyan wrote:
>Are you doing that via:
>
> fallback => 1
>
>in the argument list to 'use overload'? That's how the implicit
>definitions of operators work. It works for me:
>
>#!/usr/bin/perl -wl
>
>use overload (
> '+' => \&add,
> '+0' => \&num,
> '""' => \&num,
> fallback => 1,
>);
>
>sub add {
> my ($l, $r, $swap) = @_;
> ($l, $r) = ($r, $l) if $swap;
> my $sum = (ref($l) ? $l->[0] : $l) + (ref($r) ? $r->[0] : $r);
> return $sum;
>}
>
>sub num { $_[0][0] }
>
>$x = bless [ 10 ], 'main';
>print $x; # 10
>print $x + 3; # 13
>$x += 6;
>print $x; # 16
>
>__END__
