Data-AsObject - README

NAME

Data::AsObject - Easy OO access to complex perl data structures

VERSION

version 0.07

SYNOPSIS

use Data::AsObject qw(dao);

        my $book = dao {
            name      => "Programming Perl",
            authors   => ["Larry Wall", "Tom Christiansen", "Jon Orwant"],

        };

        print $book->name                # prints "Programming Perl"
        print $book->authors(0)          # prints "Larry Wall"
        my $array_ref = $book->authors   # $array_ref is ["Larry Wall", "Tom Christiansen", "Jon Orwant"]
        my @array = $book->authors->list # @array is ("Larry Wall", "Tom Christiansen", "Jon Orwant")
        $book->{publisher} = "O'Reilly";
        print $book->publisher           # prints "O'Reilly"

DESCRIPTION

"Data::AsObject" provides easy object-oriented access to complex and arbitrarily nested perl data structures. It is particularly suitable for working with hash-based representation of XML data, as generated by modules like XML::Complie or XML::TreePP.

WARNING

Version 0.06 of "Data::AsObject" broke backward compatibility with two changes that may break existing scripts.

Automatic dereferencing in list context is no longer provided. Use the "list" method instead.
An attempt to access an non-existing hash key by default now dies rather than simply produce a warning. Either explicitly request Data::AsObject not to die on missing hash keys, or use an exception handling mechanism to check if the data you want to access is actually there.

BENEFITS

These are some of the reasons why you may want to use "Data::AsObject":

Object-oriented syntax

        The object-oriented syntax may sometimes be more appropriate than
        the traditional hashref and arrayref syntax.

Protection from misspelled hash key names

        Since "Data::AsObject" does not preform any autovivification, it
        protects you from misspelling a hash key when accessing its value
        (but see also Hash::Util for more robust ways to do that).

Easy access to hash keys with non-standard symbols

        If your hashes contain a lot of keys with dashes or colons, as is
        often the case with keys representing xml element names,
        "Data::AsObject" can automatically access such keys by substituting
        underscores for the non-standard symbols.

Easy dereferencing of arrayrefs

        If you have a lot of arrayrefs in your data structure that often
        need to be traversed, e.g. with "grep", "map" or "foreach",
        "Data::AsObject" provides a "list" method on arrayrefs to
        automatically dereference them.

FUNCTIONS
"dao"
Takes as input one or more hash or array references, and returns one or more objects ("Data::AsObject::Hash" or "Data::AsObject::Array" respectively) that can be used to access the data structures via an object oriented interface.

Data::AsObject uses Sub::Exporter and allows you to import the "dao" sub in one of three modes:

strict mode

use Data::AsObject dao => { mode => 'strict' };

        In this mode (which is the default) "dao" will produce an object
        that dies whenever you try to invoke a hash key that does not exist.

loose mode

use Data::AsObject dao => { mode => 'loose' };

        In this mode "dao" will produce an object that returns "undef" and
        issues a warning whenever you try to invoke a hash key that does not
        exist.

strict mode

use Data::AsObject dao => { mode => 'silent' };

        In this mode "dao" will produce an object that returns "undef"
        whenever you try to invoke a hash key that does not exist, but does
        not complain.

USAGE
Working with hashes
To access hash elements by key, use the hash key as method name:

        my $data = dao { three => { two => { one => "kaboom" } } };
        print $data->three->two->one; # kaboom

If a hash key contains one or more colons or dashes, you can access its value by substituting underscores for the colons or dashes (the underlying hash key name is not modified).

        my $data = dao {
            'xml:lang'     => "EN",
            'element-name' => "some name",
        };

        print $data->xml_lang     # "EN"
        print $data->element_name # "some name"

Working with arrays
To access array items pass the item index as an argument to the hash that contains the array:

        my $data = dao {
            uk => ["one", "two", "three", "four"],
            spain => [
                { name => 'spanish', numbers => ["uno", "dos", "tres", "cuatro"] },
                { name => 'catalan', numbers => ["un", "dos", "tres", "quatre"] },
            ];
        };

        print $data->en(1) # two
        print $data->spain(0)->numbers(3); # cuatro

Array of array structures are a little bit clumsier to work with. You will need to use the "get" method of "Data::AsObject::Array" and pass it the index of the item you want to access:

        my $data = dao [
            ["one", "two", "three", "four"]
            ["uno", "dos", "tres", "cuatro"],
            ["un", "dos", "tres", "quatre"],
        ];

        print $data->get(2)->get(0); # un

Arrayrefs have a dereferencing "list" method. For example:

        my $data = dao {
            spain => [
                { name => 'spanish', numbers => ["uno", "dos", "tres", "cuatro"] },
                { name => 'catalan', numbers => ["un", "dos", "tres", "quatre"] },
            ];
        };

        foreach my $n ( $data->spain->list ) {
            print $n->name . " ";
        } # spanish catalan

Modifying data
"Data::AsObject" only provides accessor functions. To modify data, access the respective hash or array element directly:

        my $data = dao {};
        $data->{one} = "uno";
        print $data->one # uno

Autovivification
No autovivification is performed by default (but see FUNCTIONS above). An attempt to access a hash or array element that does not exist will produce a fatal error. Use an exception handling mechanism such as Try::Tiny.

use Try::Tiny;

        my $data = dao {
            uk      => ["one", "two", "three", "four"],
            spain   => ["uno", "dos", "tres", "cuatro"],
            germany => ["eins", "zwei", "drei", "vier"].
        };

        try {
            my $numbers = $data->bulgaria;
        } catch {
            warn "No info about Bulgaria!";
        };