/ 
ObjectTools-1
/ Object::props

NAME

Object::props - Pragma to implement lvalue accessors with options

VERSION 1.0

Included in ObjectTools 1.0 distribution.

SYNOPSIS

Class

package MyClass ;

# implement constructor without options
use Object::new ;

# just accessors without options (list of strings)
use Object::props @prop_names ;

# a property with validation and default (list of hash refs)
use Object::props { name       => 'digits',
                    validation => sub{ /^\d+\z/ }       # just digits
                    default    => 10
                  } ;

# a group of properties with common full options
use Object::props { name       => \@other_prop_names,   # array ref
                    default    => 'something' ,
                    validation => sub{ /\w+/ }
                    protected  => 1
                  } ;
                  
# all the above in just one step (list of strings and hash refs)
use Object::props @prop_names ,
                  { name       => 'digits',
                    validation => sub{ /^\d+\z/ }
                    default    => 10
                  } ,
                  { name       => \@other_prop_names,
                    default    => 'something' ,
                    validation => sub{ /\w+/ }
                    protected  => 1
                  } ;

Usage

my $object = MyClass->new(digits => '123');

$object->digits    = '123';

$object->digits('123');

my $d = $object->digits;  # $d == 123

undef $object->digits     # $object->digits == 10 (default)

# This would croak
$object->digits    = "xyz";

DESCRIPTION

This pragma easily implements lvalue accessor methods for the properties of your object (lvalue means that you can create a reference to it, assign to it and apply a regex to it).

You can completely avoid to write the accessor by just declaring the names and eventually the default value, validation code and other option of your properties.

INSTALLATION

Prerequisites
Perl version >= 5.6.1
CPAN
perl -MCPAN -e 'install ObjectTools'
Standard installation

From the directory where this file is located, type:

perl Makefile.PL
make
make test
make install

OPTIONS

name

The name of the property is used as the identifier to create the accessor method, and as the key of the blessed object hash.

Given 'my_prop' as the property name:

$object->my_prop = 10 ;  # assign 10 to $object->{my_prop}
$object->my_prop( 10 );  # assign 10 to $object->{my_prop}

# same thing if MyClass::new is implemented
# by the Object::new pragma

$object = MyClass->new( my_prop => 10 );

You can group properties that have the same set of option by passing a reference to an array containing the names. If you don't use any option you can pass a list of plain names as well. See "SYNOPSYS".

default

The property will be initially set to the default value. If you don't set any default option the empty string will be used as default. You can reset a property to its default value by assigning it the undef value.

# this will reset the property to its default
$object->my_prop = undef ;

# this works as well
undef $object->my_prop ;

If any validation option is set, then the default value is validated at compile time. If no default option is set, then the empty string is used bypassing the validation sub.

validation

You can set a code reference to validate a new value. If you don't set any validation option, no validation will be done on the assignment.

In the validation code, the object is passed in $_[0] and the value to be validated is passed in $_[1] and for regexing convenience it is aliased in $_. Assign to $_ in the validation code to change the actual imput value.

# web color validation
use Object::props { name       => 'web_color'
                    validation => sub { /^#[0-9A-F]{6}$/ }
                  }

# this will uppercase all input value
use Object::props { name       => 'uppercase_it'
                    validation => sub { $_ = uc }
                  }
# this would croak
$object->web_color = 'dark gray'

# when used
$object->uppercase_it = 'abc' # real value will be 'ABC'

The validation code should return true on success and false on failure. Croak explicitly if you don't like the default error message.

protected

Set this option to a true value and the property will be turned read-only when used from outside its class or sub-classes. This allows you to normally read and set the property from your class but it will croak if your user tries to set it.

BUGS

None known, but the module is not completely tested.

CREDITS

Thanks to Juerd Waalboer (http://search.cpan.org/author/JUERD) that with its Attribute::Property inspired the creation of this distribution.