Twelve Talks in One

Subclassing

Example: Add a code preprocessing step
Create subclass, add preprocessor method:

            sub preprocessor {
              my ($self, $pp) = @_;
              $self->{PREPROCESSOR} = $pp;
            }

Override ->compile() method:

            sub compile {
              my ($self, $code) = @_;
              if (defined $self->{PREPROCESSOR}) {
                $code = $self->{PREPROCESSOR}->($code);
              }
              return $self->SUPER::compile($code);
            }

Problems: Representation and interface dependency
Solution: Subclassing interface contracts?

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