Data::AsObject(3) User Contributed Perl Documentation Data::AsObject(3)NAMEData::AsObject - Easy OO access to complex perl data structures
VERSION
version 0.07
SYNOPSIS
use Data::AsObjectqw(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!";
};
See also "can" below.
"Data::AsObject::Hash" and special methods
If $data isa "Data::AsObject::Hash":
can "$data->can" will return the value of the "$data->{can}" element.
"$data->can("some_hash_key")" will properly return "undef" if
"some_hash_key" does not exists, or a reference to a sub that
returns "$data->{some_hash_key}" otherwise.
my $data = dao {
uk => ["one", "two", "three", "four"],
# ...
};
warn "No info about Bulgaria!" unless $data->can('bulgaria');
VERSION
Calling "$data->VERSION" will attempt to return the value of a hash
element with a key "VERSION". Use "Data::AsObject->VERSION"
instead.
others special methods
All other special methods and functions ("isa", "ref", "DESTROY")
should behave as expected.
BUGS
Please report any bugs or feature requests to "bug-data-object at
rt.cpan.org", or through the web interface at
http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Data-Object
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Data-Object>. I will
be notified, and then you'll automatically be notified of progress on
your bug as I make changes.
SEE ALSO
· Hash::AsObject
AUTHOR
Peter Shangov <pshangov@yahoo.com>
COPYRIGHT AND LICENSE
This software is copyright (c) 2011 by Peter Shangov.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
perl v5.14.1 2011-04-01 Data::AsObject(3)
