Overriding builtins, functions or object methods means defining subs which replace them at runtime. Overloading is a related, overlapping, concept for operators and methods which it is enlightening to compare.

See perlsub, perldata on typeglobs, the perlobj family of docs, and the overload pragma. That is nowhere near an exhaustive list. You'll know a lot when you get comfortable with this question.

What do you wish to override?

$property = $theft;
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use override qw(concept1 concept2 ...);
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Dave.

Does this help?

package Base;

sub new {
   my ($class) = @_;
   return bless({}, $class);
}

sub method { print("Base.\n") }


package Child;

our @ISA = 'Base';

sub method { print("Child!\n") }


package main;

my $o;
$o = Base->new();
$o->method();
$o = Child->new();
$o->method();
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