Bug #21255 for Time-Piece: NOTDATE - DATE should stringify DATE and let Perl handle things.

Here's the patch. It was basically a one-liner, but I included a big comment, a line in the Changes file, and a test for t/06subclass.t.

Index: Changes =================================================================== RCS file: /cvsroot/Time-Piece/Changes,v retrieving revision 1.1.1.1 diff -u -p -r1.1.1.1 Changes --- Changes 8 Sep 2006 17:14:13 -0000 1.1.1.1 +++ Changes 8 Sep 2006 17:42:57 -0000 @@ -1,6 +1,10 @@ Time::Piece Changes +1.12 + - Subtract now stringifies times subtracted from unrecognized objects + (bug #21255). + 1.11 - Skip %V test on Win32 Index: Piece.pm =================================================================== RCS file: /cvsroot/Time-Piece/Piece.pm,v retrieving revision 1.1.1.1 diff -u -p -r1.1.1.1 Piece.pm --- Piece.pm 8 Sep 2006 17:14:13 -0000 1.1.1.1 +++ Piece.pm 8 Sep 2006 17:42:57 -0000 @@ -540,7 +540,17 @@ sub subtract { if (UNIVERSAL::isa($rhs, 'Time::Seconds')) { $rhs = $rhs->seconds; } - die "Can't subtract a date from something!" if shift; + + if (shift) + { + # SWAPED is set (so someone tried an expression like NOTDATE - DATE). + # Imitate Perl's standard behavior and return the result as if the + # string $time resolves to was subtracted from NOTDATE. This way, + # classes which override this one and which have a stringify function + # that resolves to something that looks more like a number don't need + # to override this function. + return $rhs - "$time"; + } if (UNIVERSAL::isa($rhs, 'Time::Piece')) { return Time::Seconds->new($time->epoch - $rhs->epoch); Index: t/06subclass.t =================================================================== RCS file: /cvsroot/Time-Piece/t/06subclass.t,v retrieving revision 1.1.1.1 diff -u -p -r1.1.1.1 06subclass.t --- t/06subclass.t 8 Sep 2006 17:14:13 -0000 1.1.1.1 +++ t/06subclass.t 8 Sep 2006 17:42:57 -0000 @@ -45,3 +45,22 @@ for my $method (qw(new localtime gmtime) use base qw(Time::Piece); # this package is identical, but will be ->isa('Time::Piece::Twin'); } + +{ + my $class = "Time::Piece::NumString"; + my $piece = $class->strptime ("2006", "%Y"); + is (2007 - $piece, 1, + "subtract attempts stringify for unrecognized objects."); +} + +## Below is a package which only changes the stringify function. +{ + package Time::Piece::NumString; + use base qw(Time::Piece); + use overload '""' => \&_stringify; + sub _stringify + { + my $self = shift; + return $self->strftime ("%Y"); + } +}