# phpman > perldoc > Class::Virtually::Abstract

## NAME
    [Class::Virtually::Abstract](https://www.chedong.com/phpMan.php/perldoc/Class%3A%3AVirtually%3A%3AAbstract/markdown) - Compile-time enforcement of [Class::Virtual](https://www.chedong.com/phpMan.php/perldoc/Class%3A%3AVirtual/markdown)

## SYNOPSIS
      package [My::Virtual::Idaho](https://www.chedong.com/phpMan.php/perldoc/My%3A%3AVirtual%3A%3AIdaho/markdown);
      use base qw([Class::Virtually::Abstract](https://www.chedong.com/phpMan.php/perldoc/Class%3A%3AVirtually%3A%3AAbstract/markdown));

      __PACKAGE__->virtual_methods(qw(new foo bar this that));


      package [My::Private::Idaho](https://www.chedong.com/phpMan.php/perldoc/My%3A%3APrivate%3A%3AIdaho/markdown);
      use base qw([My::Virtual::Idaho](https://www.chedong.com/phpMan.php/perldoc/My%3A%3AVirtual%3A%3AIdaho/markdown));

      sub new { ... }
      sub foo { ... }
      sub bar { ... }
      sub this { ... }
      # oops, forgot to implement that()!!  Whatever will happen?!


      # Meanwhile, in another piece of code!
      # KA-BLAM!  [My::Private::Idaho](https://www.chedong.com/phpMan.php/perldoc/My%3A%3APrivate%3A%3AIdaho/markdown) fails to compile because it didn't
      # fully implement [My::Virtual::Idaho](https://www.chedong.com/phpMan.php/perldoc/My%3A%3AVirtual%3A%3AIdaho/markdown).
      use [My::Private::Idaho](https://www.chedong.com/phpMan.php/perldoc/My%3A%3APrivate%3A%3AIdaho/markdown);

## DESCRIPTION
    This subclass of [Class::Virtual](https://www.chedong.com/phpMan.php/perldoc/Class%3A%3AVirtual/markdown) provides compile-time enforcement. That means subclasses of your
    virtual class are required to implement all virtual methods or else it will not compile.

BUGS and CAVEATS
    Because this relies on import() it is important that your classes are used instead of required.
    This is a problem, and I'm trying to figure a way around it.

    Also, if a subclass defines its own import() routine (I've done it) [Class::Virtually::Abstract](https://www.chedong.com/phpMan.php/perldoc/Class%3A%3AVirtually%3A%3AAbstract/markdown)'s
    compile-time checking is defeated.

    Got to think of a better way to do this besides import().

## AUTHOR
    Original idea and code from Ben Tilly's AbstractClass
    <http://www.perlmonks.org/index.pl?node_id=44300&lastnode_id=45341>

    Embraced and Extended by Michael G Schwern <<schwern@pobox.com>>

## SEE ALSO
    [Class::Virtual](https://www.chedong.com/phpMan.php/perldoc/Class%3A%3AVirtual/markdown)