[Fwd: DateTime::Duration patch]

[Max Maischein]

Hello again,

this is the patch, which allows for DateTime::Duration comparisions. It 
has no error checking for the border cases (yet), but the patched module 
still passes all tests, so I consider that "good enough". It certainly 
is good enough for my cases where I have differences that always are far 
enough apart.

-max

-------- Original Message --------
Subject: DateTime::Duration patch
Date: Tue, 11 Nov 2003 15:30:32 +0100
From: Max Maischein <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]
Hello Dave,

after some thinking about how to compare the "inconvertible" units, I
came up with an ugly hack that will work for "most" cases - the border
cases where it fails, are not yet detected, but I'm working on that. The
patch passes all my ad-hoc tests, I'll run it later against the DateTime
test suite.
I base the "sign" determination on the fact that every day is at least
23 hours long, and that every month is at least 24*28 hours long (as DST
never occurs in february). So I can convert days and months down to
minutes and see whether the sign is positive or negative.
-max

sub add_duration
{
    my ( $self, $dur ) = @_;
    foreach ( qw( months days minutes seconds nanoseconds ) )
    {
        $self->{$_} += $dur->{$_};
    }
    # we might have to normalize_nanoseconds before comparing durations
    $self->_normalize_nanoseconds if $self->{nanoseconds};
    $self->_normalize_sign;
    return $self;
}
sub _normalize_sign {
  my $self = shift;
  my $minutes = $self->{minutes};
  # A day is longer than (or equal to) 23 hours,
  # a month is longer than (or equal to) 28 days a 24 hours, as DST is
never in february:
  $minutes += $self->{days} * 23 * 60;
  $minutes += $self->{months} * 24 * 60 * 28;
  $self->{sign} = 0 <=> $minutes;
};
sub _cmp_datetime {
  my ($left,$right,$reverse) = @_;
  ($left,$right) = ($right,$left) if $reverse;
  my $diff = $right - $left;
  #warn sprintf "Left  is  %s days and %s minutes.\n",
$left->delta_days,  $left->delta_minutes;
  #warn sprintf "Right is  %s days and %s minutes.\n",
$right->delta_days, $right->delta_minutes;
  #warn "positive"
  #  if $diff->is_positive;
  #warn "negative"
  #  if $diff->is_negative;
  return $diff->{sign};
};