Implement support for __add__ and __sub__ and basic timedelta math

p5lib/Python2/Internals.pm

@@ -128,6 +128,8 @@ my $arithmetic_operations = {
     '+' => sub {
         my ($left, $right) = @_;
 
+        return $left->__add__($right) if $left->can('__add__');
+
         if ($left->isa('Python2::Type::Scalar::Num') and ($right->isa('Python2::Type::Scalar::Num'))) {
             return \Python2::Type::Scalar::Num->new($left->__tonative__ + $right->__tonative__);
         }
@@ -149,6 +151,8 @@ my $arithmetic_operations = {
     '-' => sub {
         my ($left, $right) = @_;
 
+        return $left->__sub__($right) if $left->can('__add__');
+
         $left  = $left->__tonative__;
         $right = $right->__tonative__;
 

p5lib/Python2/Type/Object/StdLib/datetime/timedelta.pm

@@ -13,6 +13,17 @@ use Scalar::Util::Numeric qw(isfloat);
 
 sub new { bless({}, shift); }
 
+sub new_from_duration {
+    my ($self, $duration) = @_;
+
+    die Python2::Type::Exception->new('TypeError', 'new_from_duration() expects a DateTime::Duration object, got ' . ref($duration))
+        unless ref($duration) eq 'DateTime::Duration';
+
+    return \bless({
+        duration => $duration
+    }, ref($self));
+}
+
 sub __call__ {
     my $self = shift;
     my $named_arguments = pop;
@@ -103,4 +114,30 @@ sub __print__ {
     return sprintf("%s:%s:%s", $h, $m, $s);
 }
 
+sub __tonative__ { shift->{duration} }
+
+sub __add__ {
+    my ($self, $other) = @_;
+
+    die Python2::Type::Exception->new('TypeError', 'Unsupported type for addition to timedelta: ' . $other->__type__ . ', expected timedelta.')
+        unless ref($other) eq ref($self);
+
+    return $self->new_from_duration(
+        $self->__tonative__ + $other->__tonative__
+    );
+}
+
+sub __sub__ {
+    my ($self, $other) = @_;
+
+    die Python2::Type::Exception->new('TypeError', 'Unsupported type for subtraction to timedelta: ' . $other->__type__ . ', expected timedelta.')
+        unless ref($other) eq ref($self);
+
+    return $self->new_from_duration(
+        $self->__tonative__ - $other->__tonative__
+    );
+}
+
+
+
 1;

t/output-comparison-python-interpreter/stdlib-datetime-timedelta-math.py

@@ -0,0 +1,14 @@
+from datetime import timedelta
+
+print(timedelta(1) + timedelta(2))
+print(timedelta(2) - timedelta(1))
+
+try:
+    timedelta(1) + 'a'
+except TypeError:
+    print "timedelta addition with invalid type raises TypeError, as expected."
+
+try:
+    timedelta(1) - 'a'
+except TypeError:
+    print "timedelta subtraction with invalid type raises TypeError, as expected."