/ 
Class-Accessor-Validated-0.04
/ Class::Accessor::Validated

NAME

Class::Accessor::Validated - Drop-in constructor validation for Class::Accessor::Fast-based classes

VERSION

Version 0.04

SYNOPSIS

package MyApp::Thing;

use parent 'Class::Accessor::Validated';

our %ATTRIBUTES = (
    id   => 1,    # required
    name => 0,    # optional
);

__PACKAGE__->setup_accessors(keys %ATTRIBUTES);

# Then in code:
my $thing = MyApp::Thing->new({ id => 123 });

DESCRIPTION

Class::Accessor::Validated extends Class::Accessor::Fast to add lightweight constructor-time validation for required and unexpected arguments.

It supports the same hashref-based constructor pattern, and requires you to define a %ATTRIBUTES hash in your class (or inherited from a parent class) to indicate which keys are required. Any key passed to the constructor must correspond to an existing accessor.

This module is designed to be a minimal and backward-compatible validator that requires no additional dependencies or heavy OO layers.

ADDITIONAL DETAILS

This module can also be used immediately in new subclasses, even when the parent class does not itself inherit from Class::Accessor::Validated. As long as the subclass defines a %ATTRIBUTES hash and installs its accessors using setup_accessors, the constructor validation will function correctly. This makes it possible to incrementally adopt validation in an existing hierarchy without modifying base classes - a practical solution for modernizing older code or introducing stricter argument checking in new layers of functionality.

Even in the absence of a %ATTRIBUTES hash, the constructor will still validate all arguments against the set of defined accessors. Any option that does not correspond to known accessors (either get_foo and set_foo or just foo) will be flagged as invalid.

You are encouraged to follow_best_practice since methods that are not named set_ or get_ may be mistaken for accessors.

However, any option that does match a known accessor but is not listed in %ATTRIBUTES will be assumed to be optional. This allows subclasses to define additional accessors without needing to explicitly extend %ATTRIBUTES, and enables gradual adoption in codebases where base classes are not yet updated for validation.

METHODS AND SUBROUTINES

new

my $obj = My::Class->new({ foo => 1, bar => 2 });

The constructor performs the following checks:

  • Any key passed must match an existing accessor (get_foo, foo, etc.)

  • If a key is listed in %ATTRIBUTES with a true value, it is considered required

  • Keys not in %ATTRIBUTES are assumed optional as long as accessors exist

  • If invalid or missing keys are detected, the constructor throws an error

setup_accessors

Class::Accessor::Validated->setup_accessors(__PACKAGE__, @keys);

Convenience method to install accessors and apply follow_best_practice for the calling package. This avoids having to explicitly use Class::Accessor in each class.

GLOBAL VARIABLES

$Class::Accessor::Validated::ALLOW_BAD_PRACTICE

If set to a true value, constructor validation will accept any method name (e.g., foo) as a valid accessor, even if it does not follow the get_foo/set_foo naming pattern. This is useful for backward compatibility with older Class::Accessor::Fast code.

Defaults to false. Best practice is to use follow_best_practice so that accessors are unambiguously named and validated.

USAGE PATTERN

To use this module:

  • Inherit from Class::Accessor::Validated

  • Declare a %ATTRIBUTES hash in your package

  • Call setup_accessors() with the list of keys

Subclasses do not need to redefine %ATTRIBUTES unless they want to introduce new required keys.

SEE ALSO

Class::Accessor, Class::Accessor::Fast

AUTHOR

Rob Lauer

LICENSE

This module is released under the same terms as Perl itself.