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Class::Container is a Perl module with Glues object frameworks together transparently.

SYNOPSIS

package Car;
use Class::Container;
@ISA = qw(Class::Container);

__PACKAGE__->valid_params
(
paint => {default => burgundy},
style => {default => coupe},
windshield => {isa => Glass},
radio => {isa => Audio::Device},
);

__PACKAGE__->contained_objects
(
windshield => Glass::Shatterproof,
wheel => { class => Vehicle::Wheel,
delayed => 1 },
radio => Audio::MP3,
);

sub new {
my $package = shift;

# windshield and radio objects are created automatically by
# SUPER::new()
my $self = $package->SUPER::new(@_);

$self->{right_wheel} = $self->create_delayed_object(wheel);
... do any more initialization here ...
return $self;
}

This class facilitates building frameworks of several classes that inter-operate. It was first designed and built for HTML::Mason, in which the Compiler, Lexer, Interpreter, Resolver, Component, Buffer, and several other objects must create each other transparently, passing the appropriate parameters to the right class, possibly substituting other subclasses for any of these objects.

The main features of Class::Container are:

Explicit declaration of containment relationships (aggregation, factory creation, etc.)
Declaration of constructor parameters accepted by each member in a class framework
Transparent passing of constructor parameters to the class that needs them
Ability to create one (automatic) or many (manual) contained objects automatically and transparently

Class::Struct::FIELDS module combine Class::Struct, base and fields.

SYNOPSIS

(This page documents Class::Struct::FIELDS v.1.1.)
use Class::Struct::FIELDS;
# declare struct, based on fields, explicit class name:
struct (CLASS_NAME => { ELEMENT_NAME => ELEMENT_TYPE, ... });

use Class::Struct::FIELDS;
# declare struct, based on fields, explicit class name
# with inheritance:
struct (CLASS_NAME => [qw(BASE_CLASSES ...)],
{ ELEMENT_NAME => ELEMENT_TYPE, ... });

package CLASS_NAME;
use Class::Struct::FIELDS;
# declare struct, based on fields, implicit class name:
struct (ELEMENT_NAME => ELEMENT_TYPE, ...);

package CLASS_NAME;
use Class::Struct::FIELDS;
# declare struct, based on fields, implicit class name
# with inheritance:
struct ([qw(BASE_CLASSES ...)], ELEMENT_NAME => ELEMENT_TYPE, ...);

package MyObj;
use Class::Struct::FIELDS;
# declare struct with four types of elements:
struct (s => $, a => @, h => %, x => &, c => My_Other_Class);

$obj = new MyObj; # constructor

# scalar type accessor:
$element_value = $obj->s; # element value
$obj->s (new value); # assign to element

# array type accessor:
$ary_ref = $obj->a; # reference to whole array
$ary_element_value = $obj->a->[2]; # array element value
$ary_element_value = $obj->a (2); # same thing
$obj->a->[2] = new value; # assign to array element
$obj->a (2, newer value); # same thing

# hash type accessor:
$hash_ref = $obj->h; # reference to whole hash
$hash_element_value = $obj->h->{x}; # hash element value
$hash_element_value = $obj->h (x); # same thing
$obj->h->{x} = new value; # assign to hash element
$obj->h (x, newer value); # same thing

# code type accessor:
$code_ref = $obj->x; # reference to code
$obj->x->(...); # call code
$obj->x (sub {...}); # assign to element

# regexp type accessor:
$regexp = $obj->r; # reference to code
$string =~ m/$obj->r/; # match regexp
$obj->r (qr/ ... /); # assign to element

# class type accessor:
$element_value = $obj->c; # object reference
$obj->c->method (...); # call method of object
$obj->c (My_Other_Class::->new); # assign a new object

Class::Struct::FIELDS exports a single function, struct. Given a list of element names and types, and optionally a class name and/or an array reference of base classes, struct creates a Perl 5 class that implements a "struct-like" data structure with inheritance.

The new class is given a constructor method, new, for creating struct objects.
Each element in the struct data has an accessor method, which is used to assign to the element and to fetch its value. The default accessor can be overridden by declaring a sub of the same name in the package. (See Example 2.)

Each elements type can be scalar, array, hash, code or class.

Class::Contract - Design-by-Contract OO in Perl.

SYNOPSIS

package ClassName
use Class::Contract;

contract {
inherits BaseClass;

invar { ... };

attr data1;
attr data2 => HASH;

class attr shared => SCALAR;

ctor new;

method methodname;
pre { ... };
failmsg Error message;

post { ... };
failmsg Error message;

impl { ... };

method nextmethod;
impl { ... };

class method sharedmeth;
impl { ... };

# etc.
};

Background

Design-by-contract is a software engineering technique in which each module of a software system specifies explicitly what input (or data or arguments) it requires, and what output (or information or results) it guarantees to produce in response.

These specifications form the "clauses" of a contract between a module and the client software that uses it. If the client software abides by the input requirements, the module guarantees to produce the correct output. Hence by verifying these clauses at each interaction with a module, the overall behaviour of the system can be confidently predicted.
Design-by-contract reinforces the benefits of modular design techniques by inserting explicit compile-time or run-time checks on a contract. These checks are most often found in object-oriented languages and are typically implemented as pre-conditions and post-conditions on methods, and invariants on classes.

Note that these features differ from simple verification statements such as the C assert statement. Conditions and invariants are properties of a class, and are inherited by derived classes.

An additional capacity that is often provided in design-by-contract systems is the ability to selectively disable checking in production code. This allows the contractual testing to be carried out during implementation, without impinging on the performance of the final system.

Adding design-by-contract to Perl

The Class::Contract module provides a framework for specifying methods and attributes for a class (much like the existing class definition modules Class::Struct, Class::MethodMaker, and Class::Generate). Class::Contract allows both per-object and per-class methods and attributes to be defined. Attributes may be scalar-, array-, hash-, or object-based.

Class::Contract differs from other class-specification modules (except Class::Generate) in that it also provides the ability to specify invariant conditions on classes, and pre- and post-conditions on methods and attributes. All of these clauses are fully inheritable, and may be selectively disabled. It differs from all other modules in that it has a cleaner, simpler specification syntax, and -- more importantly -- it enforces encapsulation of object attributes, thereby ensuring that the class contract cannot be subverted.

Defining classes

Class::Contract provides an explicit syntax for defining the attributes, methods, and constructors of a class. The class itself is defined using the contract subroutine. contract takes a single argument -- a subroutine reference or a block. That block is executed once and the results used to construct and install the various components of the class in the current package:

package Queue;
contract {
# specification of class Queue attributes and methods here
};

Class::ObjectTemplate is a Perl extension for an optimized template builder base class.

SYNOPSIS

package Foo;
use Class::ObjectTemplate;
require Exporter;
@ISA = qw(Class::ObjectTemplate Exporter);

attributes(one, two, three);

# initialize will be called by new()
sub initialize {
my $self = shift;
$self->three(1) unless defined $self->three();
}

use Foo;
$foo = Foo->new();

# store 27 in the one attribute
$foo->one(27);

# check the value in the two attribute
die "should be undefined" if defined $foo->two();

# set using the utility method
$foo->set_attribute(one,27);

# check using the utility method
$two = $foo->get_attribute(two);

# set more than one attribute using the named parameter style
$foo->set_attributes(one=>27, two=>42);

# or using array references
$foo->set_attributes([one,two],[27,42]);

# get more than one attribute
@list = $foo->get_attributes(one, two);

# get a list of all attributes known by an object
@attrs = $foo->get_attribute_names();

# check that initialize() is called properly
die "initialize didnt set three()" unless $foo->three();

Class::ObjectTemplate is a utility class to assist in the building of other Object Oriented Perl classes.

It was described in detail in the OReilly book, "Advanced Perl Programming" by Sriram Srinivasam.

Class::Cloneable is a base class for Cloneable objects.

SYNOPSIS

package MyObject;
our @ISA = (Class::Cloneable);

# calling clone on an instance of MyObject
# will give you full deep-cloning functionality

This module provides a flexible base class for building objects with cloning capabilities. This module does its best to respect the encapsulation of all other objects, including subclasses of itself. This is intended to be a stricter and more OO-ish option than the more general purpose Clone and Clone::PP modules.

Dynamic Probe Class Library (DPCL) is an object-based C++ class library that provides the necessary infrastructure to allow tool developers and sophisticated tool users to build parallel and serial tools through technology called dynamic instrumentation.
Dynamic Probe Class Library takes the basic components needed by tool developers and encapsulates them into C++ classes. Each of these classes provide the member functions necessary to interact and dynamically instrument a running application with software patches called probes.
Dynamic instrumentation provides the flexibility for tools to insert probes into applications as the application is running and only where it is needed.
Enhancements:
- This version is a minor update to DPCL that fixes a couple problems that have been reported since the v3.4.2 release

Class::Interfaces is a Per module for defining interface classes inline.

SYNOPSIS

# define some simple interfaces
use Class::Interfaces (
Serializable => [ pack, unpack ],
Printable => [ toString ],
Iterable => [ iterator ],
Iterator => [ hasNext, next ]
);

# or some more complex ones ...

# interface can also inherit from
# other interfaces using this form
use Class::Interfaces (
BiDirectionalIterator => {
isa => Iterator,
methods => [ hasPrev, prev ]
},
ResetableIterator => {
isa => Iterator,
methods => [ reset ]
},
# we even support multiple inheritance
ResetableBiDirectionalIterator => {
isa => [ ResetableIterator, BiDirectionalIterator ]
}
);

# it is also possible to create an
# empty interface, sometimes called
# a marker interface
use Class::Interfaces (
JustAMarker => undef
);

This module provides a simple means to define abstract class interfaces, which can be used to program using the concepts of interface polymorphism.

Class::AbstractLogic is a Perl module to handle Logic Abstractions.

SYNOPSIS

# the logic class definition
package My::Logic::Foo;
use Class::AbstractLogic-base;

# a logic action
action add,
needs [qw(a b)],
verify { a => sub { /^d+$/ }, b => sub { /^d+$/ } },
sub { $_{a} + $_{b} };

1;
...

# logic module manager creation
use Class::AbstractLogic;
my $calm = Class::AbstractLogic::Manager->new;

# loading a logic class
$calm->load_logic(Foo => My::Logic::Foo);

# requesting a result from a logic method
my $result = $calm->logic(Foo)->add(a => 11, b => 12);

# $result will be false if an exception was caught
if ($result) {
print result was . $result->value . "n";
}
else {
print exception raised: . $result->key . "n";
print error message: . $result->error . "n";
}