NAME
List::Objects::WithUtils - List objects, kitchen sink included
SYNOPSIS
## A small sample; consult the description, below, for links to
## extended documentation
# Import all object constructor functions:
# array immarray array_of immarray_of
# hash immhash hash_of immhash_of
use List::Objects::WithUtils;
# Import all of the above plus autoboxing:
use List::Objects::WithUtils ':all';
# Same as above, but shorter:
use Lowu;
# Most methods returning lists return new objects; chaining is easy:
array(qw/ aa Ab bb Bc bc /)
->grep(sub { /^b/i })
->map(sub { uc })
->uniq
->all; # ( 'BB', 'BC' )
# Useful utilities from other list modules are available:
my $want_idx = array(
+{ id => '400', user => 'bob' },
+{ id => '600', user => 'suzy' },
+{ id => '700', user => 'fred' },
)->first_index(sub { $_->{id} > 500 });
my $itr = array( 1 .. 7 )->natatime(3);
while ( my @nextset = $itr->() ) {
...
}
my $meshed = array(qw/ a b c d /)
->mesh( array(1 .. 4) )
->all; # ( 'a', 1, 'b', 2, 'c', 3, 'd', 4 )
my ($evens, $odds) = array( 1 .. 20 )
->part(sub { $_[0] & 1 })
->all;
my $sorted = array(
+{ name => 'bob', acct => 1 },
+{ name => 'fred', acct => 2 },
+{ name => 'suzy', acct => 3 },
)->sort_by(sub { $_->{name} });
# array() objects are mutable:
my $mutable = array(qw/ foo bar baz /);
$mutable->insert(1, 'quux');
$mutable->delete(2);
# ... or use immarray() immutable arrays:
my $static = immarray( qw/ foo bar baz / );
$static->set(0, 'quux'); # dies
$static->[0] = 'quux'; # dies
push @$static, 'quux'; # dies
# Construct a hash:
my $hash = hash( foo => 'bar', snacks => 'cake' );
# You can set multiple keys in one call:
$hash->set( foobar => 'baz', pie => 'cherry' );
# ... which is useful for merging in another (plain) hash:
my %foo = ( pie => 'pumpkin', snacks => 'cheese' );
$hash->set( %foo );
# ... or another hash object:
my $second = hash( pie => 'key lime' );
$hash->set( $second->export );
# Retrieve one value as a simple scalar:
my $snacks = $hash->get('snacks');
# ... or retrieve multiple values as an array-type object:
my $vals = $hash->get('foo', 'foobar');
# Take a hash slice of keys, return a new hash object
# consisting of the retrieved key/value pairs:
my $slice = $hash->sliced('foo', 'pie');
# Arrays inflate to hash objects:
my $items = array( qw/ foo bar baz/ )->map(sub { $_ => 1 })->inflate;
if ($items->exists('foo')) {
# ...
}
# Hashes inflate to simple objects with accessors:
my $obj = $hash->inflate;
$snacks = $obj->snacks;
# Methods returning multiple values typically return new array-type objects:
my @match_keys = $hash->keys->grep(sub { m/foo/ })->all;
my @match_vals = $hash->values->grep(sub { m/bar/ })->all;
my @sorted_pairs = hash( foo => 2, bar => 3, baz => 1)
->kv
->sort_by(sub { $_->[1] })
->all; # ( [ baz => 1 ], [ foo => 2 ], [ bar => 3 ] )
# Perl6-inspired Junctions:
if ( $hash->keys->any_items == qr/snacks/ ) {
# ... hash has key(s) matching /snacks/ ...
}
if ( $hash->values->all_items > 10 ) {
# ... all hash values greater than 10 ...
}
# Type-checking arrays via Type::Tiny:
use Types::Standard -all;
my $int_arr = array_of Int() => 1 .. 10;
# Type-checking hashes:
use Types::Standard -all;
my $int_hash = hash_of Int() => (foo => 1, bar => 2);
# Native list types can be autoboxed:
use List::Objects::WithUtils 'autobox';
my $foo = [ qw/foo baz bar foo quux/ ]->uniq->sort;
my $bar = +{ a => 1, b => 2, c => 3 }->values->sort;
# Autoboxing is lexically scoped like normal:
{ no List::Objects::WithUtils::Autobox;
[ 1 .. 10 ]->shuffle; # dies
}DESCRIPTION
A set of roles and classes defining an object-oriented interface to Perl hashes and arrays with useful utility methods, junctions, type-checking ability, and optional autoboxing. Originally derived from Data::Perl.
Uses
The included objects are useful as-is but are largely intended for use as data container types for attributes. This lends a more natural object-oriented syntax; these are particularly convenient in combination with delegated methods, as in this example:
package Some::Thing;
use List::Objects::WithUtils;
use Moo;
has items => (
is => 'ro',
builder => sub { array },
handles => +{
add_items => 'push',
get_items => 'all',
items_where => 'grep',
},
);
# ... later ...
my $thing = Some::Thing->new;
$thing->add_items(@more_items);
# Operate on all positive items:
for my $item ($thing->items_where(sub { $_ > 0 })->all) {
...
}List::Objects::Types provides Type::Tiny-based types & coercions matching the list objects provided by this distribution. These integrate nicely with typed or untyped list objects:
package Accounts;
use List::Objects::Types -types;
use Moo 2;
has usergroups => (
is => 'ro',
# +{ $group => [ [ $usr => $id ], ... ] }
# Coerced to objects all the way down:
isa => TypedHash[ TypedArray[ArrayObj] ],
coerce => 1,
builder => sub { +{} },
);
# ... later ...
my $users_in_grp = $accts->usergroups
->get($some_group)
->grep(sub { $_[0]->get(0) });
Objects
Arrays
array (List::Objects::WithUtils::Array) provides basic mutable ARRAY-type objects. Behavior is defined by List::Objects::WithUtils::Role::Array; look there for documentation on available methods.
immarray is imported from List::Objects::WithUtils::Array::Immutable and operates much like an array, except methods that mutate the list are not available; using immutable arrays promotes safer programming patterns.
array_of provides Type::Tiny-compatible type-checking array objects that can coerce and check their values as they are added; see List::Objects::WithUtils::Array::Typed.
immarray_of provides immutable type-checking arrays; see List::Objects::WithUtils::Array::Immutable::Typed.
Hashes
hash is the basic mutable HASH-type object imported from List::Objects::WithUtils::Hash; see List::Objects::WithUtils::Role::Hash for documentation.
immhash provides immutable (restricted) hashes; see List::Objects::WithUtils::Hash::Immutable.
hash_of provides Type::Tiny-compatible type-checking hash objects; see List::Objects::WithUtils::Hash::Typed.
immhash_of provides immutable type-checking hashes; see List::Objects::WithUtils::Hash::Immutable::Typed.
Importing
A bare import list (use List::Objects::WithUtils;) will import all of the object constructor functions described above; they can also be selectively imported, e.g.:
use List::Objects::WithUtils 'array_of', 'hash_of';Importing autobox lexically enables List::Objects::WithUtils::Autobox, which provides List::Objects::WithUtils::Array or List::Objects::WithUtils::Hash methods for native ARRAY and HASH types.
Importing all or :all will import all of the object constructors and additionally turn autobox on; use Lowu; is a shortcut for importing all.
Debugging
Most methods belonging to these objects are heavily micro-optimized -- at the cost of useful error handling.
Since there are few built-in argument checks, a mistake in your code can frequently lead to slightly cryptic errors from the perl side:
> my $pos; # whoops, I'm still undefined later:
> if ($arr->exists($pos)) { ... }
Use of uninitialized value in numeric le (<=) at $useless_lib_lineno... in which case Devel::Confess is likely to improve your quality of life by providing a real backtrace:
$ perl -d:Confess my_app.pl
Use of uninitialized value in numeric le (<=) at ...
[...]::Array::exists(ARRAY(0x8441068), undef) called at ...Subclassing
The importer for this package is somewhat flexible; a subclass can override import to pass import tags and a target package by feeding this package's import() a HASH:
# Subclass and import to target packages (see Lowu.pm f.ex):
package My::Defaults;
use parent 'List::Objects::WithUtils';
sub import {
my ($class, @params) = @_;
$class->SUPER::import(
+{
import => [ 'autobox', 'array', 'hash' ],
to => scalar(caller)
}
)
}Functionality is mostly defined by Roles. For example, it's easy to create your own array class with new methods:
package My::Array::Object;
use Role::Tiny::With;
# Act like List::Objects::WithUtils::Array:
with 'List::Objects::WithUtils::Role::Array',
'List::Objects::WithUtils::Role::Array::WithJunctions';
# One way to add your own functional interface:
use Exporter 'import'; our @EXPORT = 'my_array';
sub my_array { __PACKAGE__->new(@_) }
# ... add/override methods ...... in which case you may want to also define your own hash subclass that overrides array_type to produce your preferred arrays:
package My::Hash::Object;
use Role::Tiny::With;
with 'List::Objects::WithUtils::Role::Hash';
use Exporter 'import'; our @EXPORT = 'my_hash';
sub my_hash { __PACKAGE__->new(@_) }
sub array_type { 'My::Array::Object' }
# ... add/override methods ...SEE ALSO
List::Objects::WithUtils::Role::Array for documentation on the basic set of array() methods.
List::Objects::WithUtils::Role::Array::WithJunctions for documentation on array() junction-returning methods.
List::Objects::WithUtils::Array::Immutable for more on immarray() immutable arrays.
List::Objects::WithUtils::Array::Typed for more on array_of() type-checking arrays.
List::Objects::WithUtils::Array::Immutable::Typed for more on immarray_of() immutable type-checking arrays.
List::Objects::WithUtils::Role::Hash for documentation regarding hash() methods.
List::Objects::WithUtils::Hash::Immutable for more on immhash() immutable hashes.
List::Objects::WithUtils::Hash::Typed for more on hash_of() type-checking hashes.
List::Objects::WithUtils::Hash::Immutable::Typed for more on immhash_of() immutable type-checking hashes.
List::Objects::WithUtils::Autobox for details on autoboxing.
The Lowu module for a convenient importer shortcut.
List::Objects::Types for relevant Type::Tiny types.
MoopsX::ListObjects for integration with Moops class-building sugar.
AUTHOR
Jon Portnoy <avenj@cobaltirc.org>
Licensed under the same terms as Perl.
The original Array and Hash roles were derived from Data::Perl by Matthew Phillips (CPAN: MATTP), haarg, and others.
Immutable array objects were originally inspired by Const::Fast by Leon Timmermans (CPAN: LEONT), but now use tie.
Junctions are adapted from Perl6::Junction by Carl Franks (CPAN: CFRANKS)
Most of the type-checking code and other useful additions were contributed by Toby Inkster (CPAN: TOBYINK)
A significant portion of this code simply wraps other widely-used modules, especially:
Inspiration for a few pieces comes from the "classic" (version 0.33) List::MoreUtils.