Badger::Class provides a number of import hooks that you can specify when you use the module. These are mapped to Badger::Class methods that perform various tasks to help in the construction of object classes.

For example, instead of writing something like this:

package Your::Module;

use base qw( Exporter Class::Base Class::Accessor::Fast );
use constant {
    name => 'Badger',
    foo  => 'Nuts',
    bar  => 'Berries',
};
use Scalar::Util 'blessed';

our $VERSION   = 3.14;
our $DEBUG     = 0 unless defined $DEBUG;
our @EXPORTS   = qw( name );
our @EXPORT_OK = qw( foo bar );

__PACKAGE__->mk_accessors(qw(nuts berries));

You can write something like this:

package Your::Module;

use Badger::Class 
    base        => 'Badger::Base',
    version     => 3.14,
    debug       => 0,
    get_methods => 'nuts berries',
    utils       => 'blessed',
    constant    => {
        name => 'Badger',
        foo  => 'Nuts',
        bar  => 'Berries',
    },
    exports     => { 
        all => 'name',
        any => 'nuts berries',
    };

There are a number of benefits to this approach. First and foremost, it allows you to forget about much of the messy detail typically involved in class housekeeping and adopt a more declarative style of programming. You don't have to worry about the details of exporting symbols, for example. Simply declare what the module exports and leave it up to the corresponding Badger::Class method to make sure that the Badger::Exporter module is added as a subclass and the right package variables are defined. This makes life easier for you and the code more robust by reducing the chances of you doing something silly. Thus, the job gets done quicker and you get to go home early where you can be as silly as you like in your own time.

Another benefit is that it brings a degree of consistency to your code. Having more than one way to do it is all well and good for the Perl community at large. However, it's not so good when you're writing the boilerplate code for a module and are forced to use five different ways (count 'em: subclassing, import flags, imported subroutines, package variables and class methods) in the space of ten lines of code.

Badger::Class allows you to do away with all that and use a single, uniform syntax to perform all (or most) of your class metaprogramming tasks. It allows you to collect similar code in one place where it's easy to read (when you want to) and easy to ignore (when you don't). Ask Schwern about the value of skimmable code if you don't agree that it's a Good Thing[tm].

IMPORTANT: if you have a non-trivial class declaration then you should add use strict and use warnings before you use Badger::Class. Although Badger::Class will enable them both in your module, the arguments passed to Badger::Class will be evaluated before strict and warnings get enabled so any errors may go unreported.

The import hooks shown above are syntactic sugar. They're mapped to Badger::Class methods. You can call those methods yourself using the importable class subroutine.

package Your::Module;
use Badger::Module 'class';     # import class subroutine

You can also specify this using the import parameter.

use Badger::Class import => 'class';

The class subroutine returns a Badger::Class object for the current package. (NOTE: we use the term package when we're talking specifically about Perl's symbol tables - but the term is generally synonymous with class).

A Badger::Class object provides a number of methods that allow you to modify the class. For example, you can add base classes, generate accessor and mutator methods, define exportable items, and so on.

class->version(3.14);           # define $VERSION
class->base('Another::Class');  # add base class
class->accessors('foo bar');    # generate accessors
class->exports(                 # define exports
    all => '$X $Y',
)

All the class metaprogramming methods return $self so that you can chain them together like this:

class->version(3.14)
     ->base('Another::Class')
     ->accessors('foo bar')
     ->exports( all => '$X $Y' );

The above are the explicit equivalents of using the following import hooks.

use Badger::Class
    version   => 3.14,
    base      => 'Another::Class';
    accessors => 'foo bar',
    exports   => {
        all   => '$X $Y',
    };

One important benefit of using import hooks is that the methods are called at compile time. That means that any symbols defined by the hooks/methods will be available immediately. For example, the debug hook and corresponding debug() method defines a $DEBUG variable (amongst other things).

use Badger::Class
    debug => 0;

# no need to declare 'our $DEBUG' - the above import hook did that
print $DEBUG;           # 0

You can also use the class subroutine to modify remote classes, i.e. classes other than the current one.

class->('Existing::Class')->methods(
    wiz => sub {
        # new wiz() method for Existing::Class
    }
);

You can construct entirely new classes on-the-fly.

class('Amplifier')
    ->base('Badger::Base')
    ->constant( max_volume => 10 )
    ->methods( about => sub { 
          "This amp goes up to " . shift->max_volume 
      } );

Amplifier->about;                   # This amp goes up to 10

And subclasses of your new subclasses.

class('Nigels::Amplifier')
    ->base('Amplifier')
    ->constant( max_volume => 11 );

Nigels::Amplifier->about;           # This amp goes up to 11

Being able to define new class on the fly using nothing more than a handful of methods is really quite useful. You can take an existing class, subclass it, tweak it, attach some custom methods, instantiate it and then call a method on it, all in a single expression. You don't need to use any Perl statements or keywords to get the job done, so there's no need to eval any code (this should make you feel warm and fuzzy in that special Badger place if auto-generating classes is your thing).

The Badger::Class object provides a number of methods for inspecting and manipulating the current class. For example, there are methods to set and get package variables for class.

class->var( X => 10 );          # same as: $X = 10
class->var('X');                # same as: $X

In this simple example, the effect is exactly the same as modifying the $X package variable directly. However, this method (and related methods) provides an abstraction of class variables that works correctly with respect to subclassing. That is, accessing a class variable in a subclass of Your::Module will resolve to the package variable in the subclass, rather than the base class. If instead you write $X then you'll always get the variable in the base class package (which may be what you want, of course).

A form of inheritance for class variables can be implemented using the any_var() method. This looks for a package variable in the current class or in any of the base classes.

class->any_var('X');            # $X with @ISA inheritance

This idiom is particularly useful to provide default values for a class that you might want to re-define later in a subclass. We'll look at some examples of that shortly.

The Badger::Class module can itself be subclassed, allowing you to create more specialised class metaprogramming modules to suit your own needs. For a simple example, you can create a class module for a particular project that hooks into your own modules that define constants, utility functions, and so on.

# defining a Badger::Class subclass...
package My::Class;

# ...using Badger::Class, of course
use Badger::Class
    uber     => 'Badger::Class',
    constant => {
        CONSTANTS => 'My::Constants',
        UTILS     => 'My::Utils',
    };

The trick here is to use the uber hook instead of base. This is a special case that applies only when you're subclassing Badger::Class (or another module derived from Badger::Class). In addition to adding Badger::Class (or whatever class module you specify) as a base class of the current module, it also performs some extra magic to ensure that the class() and classes() subroutines return objects of your new class (e.g. My::Class) instead of Badger::Class. You don't need to worry too much about the details. Just use uber instead of base when you subclass a Badger::Class module and we'll take care of everything for you. See the uber() and UBER() methods for further details.

Once your class module is defined, you can use it to generate new classes for your application.

# defining classes using your new class module
package My::Example;

use My::Class
    version   =>  2,                     # inherited Badger::Class options
    base      => 'My::Base',
    constants => 'black white blue',     # imported from My::Constants
    utils     => 'wibble frusset pouch'; # imported from My::Utils

You can easily create your own methods and corresponding import hooks to implement whatever metaprogramming functionality you require for a particular project. Here's a trivial example which defines a method to set a $FOO package variable in the target class.

package My::Class;

use Badger::Class
    uber  => 'Badger::Class',
    hooks => 'foo';

sub foo {
    my ($self, $value) = @_;
    $self->var( FOO => $value );
}

Now you can use your class module with the foo import hook and it'll define the $FOO package variable at compile time.

package My::Example;

use My::Class
    version =>  3,
    base    => 'My::Base',
    foo     => 'Default foo value';

print $FOO;     # Default foo value

Here's a slightly more advanced example which sets the $FOO package variable as above and additionally generates a foo() method in the target class. The foo() method being generated (not to be confused with the foo() method generating it) is a simple mutator method to get or set the $this->{foo} item. We use $this to represent the object in our target class that will have the the generated foo() method called against it to avoid confusion with the $self reference which is the Badger::Class metaprogramming object. If the method doesn't find a foo value set in $this then it uses the default value defined in the $FOO package variable.

package My::Class;

use Badger::Class
    uber  => 'Badger::Class',
    hooks => 'foo';

sub foo {                                   # metaprogramming method
    my ($self, $value) = @_;
    $self->var( FOO => $value );            # define $FOO pkg var
    $self->method(                          
        foo => sub {                        # generate foo() method
            my $this = shift;               # object in target class
            return @_
                ? $this->{ foo } = shift    # set 
                : $this->{ foo }            # get
               || $this->var('FOO');        # default
        }
    );
}

It is a little confusing at first to have methods in one class generating methods in another, especially when they share the same name. However, it's probably less confusing than deliberating giving your generating and generated method different names. The hook mechanism shown above is deliberately simple, but you can roll your own more extensive mechanism using the Badger::Exporter (see the exports hook and exports() method) if you want to do something more advanced.

This constant subroutine is an alias for Badger::Class.

This subroutine returns the class name (i.e. package) of the class or object it was called against, or the package of the caller if no argument is specified.

CLASS->method;          # same as __PACKAGE__->method
$object->CLASS->method; # same as ref($object)->method

There's nothing special about the class name returned. It's just a plain text string. This is currently implemented as a runtime subroutine but will probably be changed at some point to be a compile-time constant subroutine.

This subroutine returns a Badger::Class object for the package name or object passed as an argument. If no argument is passed then it uses the package of the caller.

# Badger::Class object for current __PACKAGE__
my $class = class;

# Badger::Class object for another package
my $class = class('Another::Class');

Be aware that the Badger::Class object returns the package name when stringified (i.e. printed, appended to another string, etc). That means that you can treat it like a string for most practical purposes, even though it's actually an object.

print class;            # Your::Module

You can also call class as an object method. Perl implicitly passes the object reference (traditionally called $self) as the first argument So the class subroutine Just Works[tm] and returns a Badger::Class object for the object's class.

package Your::Module;

use Badger::Class 'class';

sub introspect {
    my $self  = shift;          # object $self is first argument
    my $class = $self->class;   # same as class($self)

    # $class is an object, but gets auto-stringified to class name
    print "I am a $class instance\n";
}

One important thing to understand is that calling class as a method will always return the relevant class for the object. If $self is an instance of Your::Module, then you'll get a Badger::Class object for Your::Module.

my $ym = Your::Module->new;
$ym->introspect;                # I am a Your::Module instance

However, if $self is an instance of a subclass of Your::Module, say, My::Module, then you'll get a Badger::Object back for My::Module instead.

package My::Module;
use base 'Your::Module';

package main;
my $mm = My::Module->new;
$mm->introspect;                # I am a My::Module instance

In this simple example it would have been just as easy to use ref to find out what kind of object we were dealing with, especially when all we're doing is printing the class name. However, things get more interesting when we combine that with the ability to inspect and define class variables.

Consider this base class module:

package Amplifier;

use Badger::Class
    base        => 'Badger::Base',
    import      => 'class',
    get_methods => 'max_volume';

our $MAX_VOLUME = 10;

sub init {
    my ($self, $config) = @_;
    $self->{ volume     } = 0;   # start quietly
    $self->{ max_volume } = $config->{ max_volume } 
        || $MAX_VOLUME;
    return $self;
}

The init() method (see Badger::Base) looks for a max_volume setting in the configuration parameters, or defaults to the $MAX_VOLUME package variable.

my $amp = Amplifer->new;      # default max_volume: 10

So you're on ten here, all the way up, all the way up, all the way up, you're on ten on your guitar. Where can you go from there? Where? Nowhere. Exactly. What we do is, if we need that extra push over the cliff, you know what we do?

my $amp = Amplifier->new( max_volume => 11 );

Eleven. Exactly. One louder.

So far, so good. But what if we wanted to make this the default? Sure, we could make ten louder and make that be the top number, or we could remember to specify the max_volume parameter each time we use it. But let's assume we're working with temperamental artistes who will be too busy worrying about the quality of the backstage catering to think about checking their volume settings before they go on stage.

Thankfully we didn't hard-code the maximum volume but used the $MAX_VOLUME package variable instead. We can change it directly like this:

$Amplifier::MAX_VOLUME = 11;

Or using the class var() method (just to show you what the roundabout way looks like):

Amplifier->class->var( MAX_VOLUME => 11 );

Either way has the desired effect of changing the default maximum volume setting without having to go and edit the source code of the module.

The downside to this is that it is an all-encompassing change that will affect all future instances of Amplifier and any subclasses derived from it that don't define their own max_volume parameter explicitly.

But what if that's not what you want? What if you're playing a Jazz/Blues festival on the Isle of Lucy, for example, or performing a musical trilogy in D minor, the saddest of all keys? In that case you don't want to change all the amplifiers, just some of them.

This is the kind of problem that is easily solved by using inheritance. Your base class amplifier defines the default properties and behaviours for the general case, leaving subclasses to reimplement anything that needs changing for more specific cases. All the bits that don't get redefined by a subclass are automatically inherited from the base class.

The only problem is that Perl's limited OO model only applies inheritance to methods and not package variables. However, we can use the Badger::Class object to roll our own inheritance mechanism for package variables where needed.

Let's look again at the relevant line from the init() method where the max_volume is set:

$self->{ max_volume } = $config->{ max_volume } 
    || $MAX_VOLUME;

Rather than accessing $MAX_VOLUME directly, we can instead use the class object to fetch the value of the $MAX_VOLUME class variable for us.

$self->{ max_volume } = $config->{ max_volume } 
    || $self->class->var('MAX_VOLUME');

This will continue to work as before for all instances of Amplifer. It's a little more long-winded and involves an extra method call or two, but it has the benefit of working correctly with respect to inheritance. That means we can now subclass Amplifier and define a different default value for $MAX_VOLUME.

package Nigels::Amplifier;
use base 'Amplifier';
our $VOLUME = 11;

The init() method will now look for the $MAX_VOLUME variable in our subclass package (Nigels::Amplifier) instead of the base class package (Amplifier).

One further enhancement we can make is to use any_var() instead of var().

$self->{ max_volume } = $config->{ max_volume } 
    || $self->class->any_var('MAX_VOLUME');

If you don't define a new $MAX_VOLUME class variable in the subclass then any_var() will walk upwards through all the base classes until it finds one that does. The end result is that your class variables will appear to be inherited from super-class to sub-class.

It's worth stressing at this point that there isn't any real inheritance going on here with respect to package variables. Nothing is being copied or shuffled around to give your subclasses the package variables that they inherit from their base classes (except perhaps for the odd bit of internal caching for the sake of efficiency). Instead it's the Badger::Class object that is smart enough to go looking for package variables in all the right places, but only if you ask it to do so.

Accessing package variables via a method is obviously going to be slower than referencing them direct. The benefit comes from flexibility and ease of use (and it's generally better to optimise for programmer convenience unless you have good reason to do otherwise). In most real-world applications, performance is unlikely to be affected to any significant degree unless you're doing it often in a speed critical section of code. If this is an issue, then you can perform the more expensive variable lookup once when the object is initialised and cache the value(s) internally for other methods to use, as shown in the earlier examples with $self->{ max_volume }.

This subroutine returns a list (in list context) or a reference to a list (in scalar context) of Badger::Class objects. As per class(), a package name or object reference should be passed as the first argument, either explicitly or implicitly by calling it as an object method.

The first Badger::Class object in the list returned represents the current class object, as would be returned by class(). Any further items in the list are Badger::Class objects representing all the base classes of the object. The order of base classes is determined by the heritage() method which implements a simplified variant of the C3 method resolution algorithm.

Allows you to define a base class or classes for the module. Multiple values can be specified by reference to an array or as a single whitespace delimited string.

# single base class
use Badger::Class
    base => 'Your::Base';

# multiple base classes as list reference
use Badger::Class
    base => ['My::Base', 'Your::Base'];

# multiple base classes as single string
use Badger::Class
    base => 'My::Base Your::Base';

If you accidentally put commas between the names in the string then we'll silently ignore them instead of chastising you for it. We know what you mean.

# commas are allowed, with or without whitespace afterwards
use Badger::Class
    base => 'My::Base,Your::Base, Another::Base';

See the base() method for further details.

This can be used to mixin subroutines, methods and/or data from another module. It works in a similar way to the regular import/export mechanism.

package Your::Module;

use Badger::Class
    mixin => 'Your::Mixin::Module';

You can specify multiple class using either a list reference or whitespace delimiter string, as per base.

package Your::Module;

use Badger::Class
    mixin => 'My::Mixin::Module Your::Mixin::Module';

The modules that you're mixing in should declare the methods that they make available for mixing using the mixins hook or mixins() method.

See the mixin() method and Badger::Mixin for further details.

This is used to declare the symbols that can be mixed into another module.

package Your::Mixin::Module;

use Badger::Class
    mixins => '$NAME nuts berries';

our $NAME = 'Badger';
sub nuts    { return 'I like nuts' }
sub berries { return 'I like berries' }

The $NAME package variable, and nuts and berries subroutines will be exported to any module that loads Your::Mixin::Module as a mixin.

package Your::Module;

use Badger::Class
    mixin => 'Your::Mixin::Module';

print $NAME;            # Badger
print nuts();           # I like nuts
print berries();        # I like berries

See the mixins() method and Badger::Mixin for further details.

This can be used to declare a version number for your module. It defines the $VERSION package variable for you along with a VERSION constant subroutine that returns the same value.

package Your::Module;

use Badger::Class
    version => 3.14;

print $VERSION;                 # 3.14
print  VERSION;                 # 3.14

package main;

print $Your::Module::VERSION;   # 3.14
print  Your::Module->VERSION;   # 3.14

See the version() method for further details.

This can be used to define a $DEBUG package variable and debugging() subroutine that you can use to get or set its value. It is typically used in conjunction with the Badger::Base debug() method like so:

package Your::Module;

use Badger::Class
    base  => 'Badger::Base',
    debug => 0;

sub some_method {
    my $self = shift;
    $self->debug("Doing some_method()\n") if $DEBUG;
}

See the debug() method and Badger::Debug for further details.

This can be used to define constants in your module.

package Your::Module;

use Badger::Class
    constant => {
        name => 'Badger',
        food => 'Nuts and Berries',
    };

print name;     # Badger
print food;     # Nuts and Berries

In works just like the constant module in defining constant subroutines that return the specified value. Perl resolves these at compile time so they're very efficient.

Thanks to the wonders of Perl's loosely defined object system, you can call these subroutines as object methods. In this case they're not resolved at compile time so they're no more efficient than regular method calls. However they do provide a useful mechanism for defining constants that can be redefined by subclasses.

package Your::Amplifier;

use Badger::Class
    constant => {
        max_volume => 10,
    };

sub how_loud {
    my $self = shift;
    print "This amp goes up to ", $self->max_volume, "\n";
}

package main;

Your::Amplifier->how_loud;  # This amp goes up to 10

This module can now be subclassed with a new max_volume defined, like so:

package My::Amplifier;

use Badger::Class
    base     => 'Your::Amplifier',
    constant => {
        max_volume => 11,
    };

package main;

My::Amplifier->how_loud;  # This amp goes up to 11

This provides an alternative to using package variables to define default configuration values for a module. The only limitation is that you can't change them once they're defined (although you can subclass the module and define a new constant). This limitation may be a Good Thing in some cases.

See the constant() method for further details.

This can be used to import one or more symbols from the Badger::Constants module (or a constants module of your choosing if you subclass Badger::Class as described above in SUBCLASSING Badger::Class).

use Badger::Class
    constants => 'ARRAY TRUE FALSE';

sub is_this_an_array_ref {
    my $thingy = shift;
    return ref $thingy eq ARRAY ? TRUE : FALSE;
}

See the constants() method and Badger::Constants for further details.

This is a short-cut for defining a number of single-word constants.

use Badger::Class
    words => 'yes no';

print yes;          # yes
print no;           # no

Defining constants for frequently used words is a good thing because it eliminates the chance of misspelling. If you misspell the name of a constant then Perl will raise an error giving you immediate notification of the problem. On the other hand, if you misspell a word in a string, then the chances are you won't find out until you next run your extensive test suite. You do have an extensive test suite don't you?

use Badger::Class
    words => 'inclusive exclusive';

sub do_something_goodly {
    my ($self, $params) = @_;

    # PASS: Perl throws an error about 'incluvise' bareword
    if ($params->{ mode } eq incluvise) {
        ... 
    }
}

sub do_something_badly {
    my ($self, $params) = @_;

    # FAIL: Perl does what you tell it and has no way of 
    # spotting your typo
    if ($params->{ mode } eq 'incluvise') {
        ...
    }
}

This allows you to pre-define one or more package variables. It works rather like the vars module.

use Badger::Class
    vars => '$FOO @BAR %BAZ';

It also allows you to provide values for variables, like so:

use Badger::Class
    vars => {
        '$FOO' => 'Hello World',
        '@BAR' => [1.618,2.718,3.142],
        '%BAZ' => { x=>10, y=>20 },
    };

See the vars() method for further information.

This allows you to declare the symbols that your module can export.

use Badger::Class
    exports => {
        all => 'foo bar',
        any => 'baz bam',
    };

See the exports() method and Badger::Exporter for further details.

This can be used to set the $THROWS package variable, as used by the error handling mechanism in Badger::Base.

package Your::Module;

use Badger::Class
    base   => 'Badger::Base',
    throws => 'oh.noes';

package main;

eval {
    Your::Module->error('something has gone wrong');
};
print $@;       # oh.noes error - something has gone wrong

See the throws() method and Badger::Base for further information.

This can be used to define a $MESSAGES package variable which references a hash array of message formats for use with the message() and related methods in Badger::Base

package Your::Module;

use Badger::Class
    base     => 'Badger::Base',
    messages => {
        request => 'can i haz %s?',
        denied  => 'FAIL: NO %s 4U!!!',
    };

package main;

print Your::Module->message( request => 'cheezburger' );
                # can i haz cheezburger?

Your::Module->warn_msg( denied => 'cheezburger' );
                # FAIL: NO cheezburger 4U!!!

See the messages() method and Badger::Base for further details.

This can be used to import symbols from the Badger::Utils module. This defines a number of its own utility functions, as well as providing access to a number of functions from Scalar::Util. (NOTE: only a limited number of functions from Scalar::Util at present but I plan to make Badger::Utils delegate to any symbols in any of the *::Util modules).

use Badger::Class
    utils => 'blessed xprintf';

sub welcome {
    my ($self, $name) = @_;

    $name = $name->get_name
        if blessed $name && $name->can('get_name');

    xprintf('Hello %s!', $name);
}

See the utils() method and Badger::Utils for further details.

This can be used to define configuration options for your module. It delegates to the Badger::Class::Config module.

package Your::Module;

use Badger::Class
    base      => 'Badger::Base',
    accessors => 'foo bar baz wig woot toot zoot zang',
    config    => [
        'foo',                      # optional item
        'bar!',                     # mandatory item
        'baz=42',                   # item with default
        'wig|wam|bam',              # item with aliases
        'woot|pkg:WOOT',            # fallback to $WOOT pkg var
        'toot|class:WOOT',          # fallback to $WOOT class var
        'zoot|method:ZOOT',         # fallback to ZOOT() method/constant
        'zing|zang|pkg:ZING=99',    # combination of above
    ];

sub init {
    my ($self, $config) = @_;

    # call the configure() method provided by the above
    $self->configure($config);

    return $self;
}

The configure() method is exported into your module as a configuration method for initialising object instances. A $CONFIG package variable is also exported containing a reduced (i.e. optimised for performance) version of the configuration scheme which the configure() method uses.

This can be used to import a single codec from Badger::Codecs.

use Badger::Class
    codec => 'base64';

my $encoded = encode('Some text');
my $decoded = decode($encoded);

See the codec() method and Badger::Codecs for further details.

This can be used to import multiple codecs from Badger::Codecs.

use Badger::Class
    codecs => 'base64 storable';

my $encoded = encode_base64( encode_storable( $some_data ) );
my $decoded = decode_storable( decode_base64( $encoded ) );

Codecs can be composed as a pipeline of other codecs. In the following example, we define a session codec which encodes data by first passing it through the storable codec (which uses the Storable freeze() subroutine) and then onto the base64 codec (which uses the MIME::Base64 encode_base64 subroutine).

use Badger::Class
    codecs => {
        session => 'base64+storable',
    };

my $encoded = encode_session( $some_data );
my $decoded = decode_session( $encoded );

In case you were wondering about the significance of this particular codec combination, the Storable module can generate NULL characters in the output stream which will make some databases (e.g. Postgres) choke. Adding a second level of Base 64 encoding solves the problem.

See the codecs() method and Badger::Codecs for further details.

This can be used to define methods for a class on-the-fly or patch existing subroutines or methods into a class.

use Badger::Class
    methods => {
        foo => sub { print "This is the foo method" },
        bar => \&Some::Other::Method,
    };

See the methods method for further details.

This can be used to define methods for list-based objects.

use Badger::Class
    slots => 'size colour object';

See the L<slots> method for further details.

This can be used to define simple read-only accessor methods for a class.

use Badger::Class
    accessors => 'foo bar';

You can use get_methods as an alias for accessors if you prefer.

use Badger::Class
    get_methods => 'foo bar';

See the accessors() method for further details.

This can be used to define simple read/write mutator methods for a class.

use Badger::Class
    mutators => 'foo bar';

You can use set_methods as an alias for mutators if you prefer.

use Badger::Class
    set_methods => 'foo bar';

See the mutators() method for further details.

This can be used to define methods for accessing hash arrays inside an object

use Badger::Class
    hash_methods => 'users addresses';

See the hash_methods() method and the hash() method in Badger::Class::Methods for further information.

This can be used to define an init() method for initialising an object. The constructed init() method stores the configuration data internally and calls each of the methods named.

use Badger::Class
    base        => 'Badger::Base',
    init_method => 'init_foo init_bar';

sub init_foo {
    my ($self, $config) = @_;
    ...
}

sub init_bar {
    my ($self, $config) = @_;
    ...
}

It is typically used in conjunction with the config hook which defines a configure() method.

use Badger::Class
    base        => 'Badger::Base',
    config      => 'x y',
    init_method => 'configure';

It can also be used to call initialisation methods inherited from base classes or imported from mixins.

use Badger::Class
    base        => 'My::Base1 My::Base2',
    init_method => 'init_base1 init_base2';

See the init_method() method and the initialiser() method in Badger::Class::Methods for further information.

This can be used as a shortcut to the overload module to overload operators for your class.

use Badger::Class
    overload => {
        '""'     => \&text,
        bool     => sub { 1 },
        fallback => 1,
    };

This is a shortcut to the overload module. It can be used to define an auto-stringification method that generates a text representation of your object. The method can be specified by name or as a code reference.

use Badger::Class
    as_text => 'your_text_method';

sub your_text_method {
    my $self = shift;
    # your code
}

This is a shortcut to the overload module. It can be used to define an method that is used for boolean truth comparisons. This can be useful in conjunction with the as_text hook to ensure that an object reference always evaluates true, even if the auto-stringification method returns a string that Perl considers false (e.g. an empty string or 0).

use Badger::Class
    as_text => 'your_text_method',
    is_true => sub { 1 };           # always true

The method can be specified as a method name or code reference. For simple false/true values you can also specify 0 or 1 and leave it up to Badger::Class to alias it to an appropriate subroutine.

use Badger::Class
    as_text => 'your_text_method',
    is_true => 1;                   # always true

This can be used to load and import symbols from the Badger::Filesystem module.

use Badger::Class
    filesystem => 'Dir File';

my $dir = Dir('/path/to/dir');

See the filesystem() method for further details.

This is a special case of the base hook which should be used when subclassing a Badger::Class class.

package Your::Class;

use Badger::Class
    uber => 'Badger::Class';

See the uber() method for further details.

This can be used by Badger::Class subclasses to define their own import hooks.

package Your::Class;

use Badger::Class
    uber  => 'Badger::Class',
    hooks => 'foo bar';

See the hooks() method for further details.

Constructor method for a Badger::Class object. You shouldn't ever need to call this method directly. Use the class() subroutine instead.

Returns the class (i.e. package) name.

print class->name;          # Your::Module

This method is called automatically whenever a Badger::Class object is stringified.

print class;                # Your::Module

The pkg() method is an alias for name() for those occasions when it reads better (for an entirely subjective definition of "better").

print class->pkg;           # Your::Module
class->pkg->new;            # Your::Module->new

Returns the package names of the immediate parents (base classes) of an object class.

The heritage() method returns a list of Badger::Class objects representing each class in the inheritance chain, starting with the current class and continuing up through its superclasses.

It uses a simplified version of the C3 method resolution algorithm. See IMPLEMENTATION NOTES for further details if you're interested in that kind of thing.

This method returns a short string used to identify the object class. This is typically used for error reporting purposes if the object doesn't explicitly define an error type (see the throws configuration option and $THROWS package variable in Badger::Base).

It generates a lower case dotted representation of the class name, with the common base part removed (Badger:: by default). For example a Badger::Example module would return example as an identifier, and Badger::Foo::Bar would return foo.bar.

This method returns Badger by default. It is used by the id() method to determine the common base part of a module name to remove when generating an identifer for error reporting.

Method to create an instance of an object class. Delegates to the new() method for the class.

Returns true or false to indicate if the module class is loaded or not.

Loads the module class if not already loaded.

A wrapper around load() which catches any errors raised by the module not being found. It returns the module name if it was loaded correctly, a false value (0) if not. If the module was found but contained syntax errors then these will be throw as errors as usual.

Returns a reference to the package symbol table for the class.

my $symbols = class->symbols;

Returns a symbol table entry for a particular name.

my $symbol = class->symbol('FOO');

Adds a new value to the symbol table.

# important a subroutine/method
class->import_symbol(
    foo => sub { ... }
);

# importing a class variable
class->import_symbol(
    BAR => \$bar,
)

Returns a reference to the SCALAR value for a name in the symbol table.

my $xref = class->scalar_ref('X');  # like: $xref = \$X;

Returns a reference to the ARRAY value for a name in the symbol table.

my $xref = class->array_ref('X');   # like: $xref = \@X;

Returns a reference to the HASH value for a name in the symbol table.

my $xref = class->hash_ref('X');    # like: $xref = \%X;

Returns a reference to the CODE value for a name in the symbol table.

my $xref = class->code_ref('X');    # like: $xref = \&X;