Inheritance

Sometimes a class almost describes what you want your object to do.  In this case, rather than copying the proper code into our own file and modifying it, we inherit from it:

    package Foo::Bar::Modified;
    require Foo::Bar;  # Get all that code.
    our @ISA = ("Foo::Bar"); # I am one of them.

At this point, an instance of Foo::Bar::Modified is exactly like a Foo::Bar, constructor, accessors and all.