On Tue Nov 10 08:22:21 2009, SHAY wrote:
Show quoted text> I find it rather unhelpful that when parse_duration() fails, it returns
> a DateTime::Duration object without producing any error. If you then
> make use of that object (and there is no reason why you wouldn't do,
> given that there was no error!) then subsequent calculations can go
> wrong because the object represents a duration of 0.
>
> Other DateTime::Format::* modules have an on_error parameter in their
> constructors to give control over the behaviour when parse_datetime()
> fails (e.g. return the undefined value, croak() or run a callback
> subroutine), and they also default to one of those behaviours. It would
> be helpful if DateTime::Format::Duration did likewise.
>
> For example, DateTime::Format::Strptime has an on_error parameter which
> defaults to 'undef', so if parse_datetime() fails then it returns the
> undefined value by default.
I would also like to see such behaviour added. Attached is a patch which adds an on_error
parameter, taking "zero" (current behaviour), "undef", or "croak" (as per other modules).
--- Duration.pm.orig 2010-02-05 19:38:39.000000000 +0000
+++ Duration.pm 2010-02-05 20:05:19.000000000 +0000
@@ -26,6 +26,7 @@
base => { type => OBJECT | UNDEF, default => undef },
normalise => { type => SCALAR, default => 0 },
normalize => { type => SCALAR, default => 0 },
+ on_error => { type => SCALAR, default => "zero" },
});
$args{normalise} ||= delete $args{normalize};
@@ -193,9 +194,9 @@
sub parse_duration {
my $self = shift;
- DateTime::Duration->new(
- $self->parse_duration_as_deltas(@_)
- );
+ my @deltas = $self->parse_duration_as_deltas(@_);
+
+ return (defined $deltas[0]) ? DateTime::Duration->new( @deltas ) : undef;
}
sub parse_duration_as_deltas {
@@ -216,9 +217,19 @@
# Run the parser
my $parser = $self->{parser} || $self->_build_parser;
- eval($parser);
+ my $retval = eval($parser);
die "Parser ($parser) died:$@" if $@;
+ if (!$retval) {
+ if ($self->{'on_error'} eq "zero") {
+ # Nothing
+ } elsif ($self->{'on_error'} eq "undef") {
+ return undef;
+ } elsif ($self->{'on_error'} eq "croak") {
+ croak "Failed to parse duration from '$time_string'";
+ }
+ }
+
$years += ($centuries * 100);
$days += ($weeks * 7 );
@@ -768,6 +779,12 @@
If a base DateTime is given then that is the normalisation date. Setting
this attribute overrides the above option and sets normalise to true.
+=item * C<on_error => $string>
+
+This controls behaviour after failing to parse a string. Can be "zero"
+(default) which returns a zero duration, "undef" which returns undef,
+or "croak" which croaks.
+
=back
=back
