add PDL::Hash to simplify hash-based PDL subclasses

Basic/Core/Core.pm

@@ -756,6 +756,16 @@ anyway.  (see L</get_dataref>.)
 
 sub topdl {PDL->topdl(@_)}
 
+####################### Subclass as hashref #######################
+{ package # hide from PAUSE
+    PDL::Hash;
+our @ISA = qw/PDL/;
+sub initialize {
+  my ($class) = @_;
+  bless { PDL => PDL->null }, ref $class || $class;
+}
+}
+
 ####################### Overloaded operators #######################
 
 { package # hide from MetaCPAN

Changes

@@ -14,6 +14,7 @@
 - add Primitive::approx_artol
 - get_dataref now works even with DONTTOUCHDATA which is really about allocation
 - if $pdl->{PDL} is code ref, $pdl now passed as arg
+- add PDL::Hash to simplify hash-based PDL subclasses
 
 2.093 2024-09-29
 - PDL.set_datatype now doesn't physicalise input, PDL.convert_type does

t/subclass.t

@@ -72,7 +72,7 @@ undef $z;
 ##  First define a PDL-derived object:
 {
 package PDL::Derived3;
-our @ISA = qw/PDL/;
+our @ISA = qw/PDL::Hash/;
 sub new {
   my ($class, $data) = @_;
   return $class->SUPER::new($data) if ref($data) ne 'PDL'; # if not object, inherited constructor
@@ -83,7 +83,7 @@ sub new {
 ####### Initialize function. This over-ridden function is called by the PDL constructors
 sub initialize {
   my ($class) = @_;
-  my $self = bless { PDL => PDL->null }, ref $class || $class;
+  my $self = $class->SUPER::initialize;
   $self->{someThingElse} = 42,
   $self;
 }
@@ -159,7 +159,7 @@ $main::OVERRIDEWORKED = 0;
 ##  First define a PDL-derived object:
 {
 package PDL::Derived4;
-our @ISA = qw/PDL/;
+our @ISA = qw/PDL::Hash/;
 sub new {
   my ($class, $data) = @_;
   return $class->SUPER::new($data) if ref($data) ne 'PDL'; # if not object, inherited constructor
@@ -172,7 +172,7 @@ sub new {
 sub initialize {
   $::INIT_CALLED = 1;
   my $class = shift;
-  my $self = bless { PDL => PDL->null }, ref $class || $class;
+  my $self = $class->SUPER::initialize;
   $self->{someThingElse} = 42,
   $self;
 }