$piddle->something()
but don't want to mess up the PDL namespace (a worthy goal, indeed!). The other is that you wish to provide special handling of some functions or more information about the data the piddle contains. In the first case, you can do with
package BAR; @ISA=qw/PDL/; sub foo {my($this) = @_; fiddle;}
package main; $a = PDL::pdl(BAR,5); $a->foo();
However, because a PDL object is an opaque reference to a C struct, it is
not possible to extend the PDL class by e.g. extra data via subclassing. To
circumvent this problem PerlDL has built-in support to extent the PDL class
via the has-a
relation for blessed hashes. You can get the HAS-A behave like
IS-A simply in that you assign the PDL
object to the attribute named PDL and redefine the method
initialize().
package FOO;
@FOO::ISA = qw(PDL); sub initialize { my $class = shift; my $self = { creation_time => time(), # necessary extension :-) PDL => null, # used to store PDL object }; bless $self, $class; }
All PDL constructor will call initialize()
to make sure that
your extentions are added by all PDL constructors automaticly. The
PDL
attribute is used by perlDL to store the PDL object and all PDL methods use
this attribute automaticly if they are called with a blessed hash reference
instead of a PDL object (a blessed scalar).
Do remember that if you subclass a class that is subclassed from a piddle, you need to call SUPER::initialize.
NEED STUFF ABOUT CODE REFs!!