NAME
MooseX::Extended - Extend Moose with safe defaults and useful features
VERSION
version 0.26
SYNOPSIS
package My::Names {
use MooseX::Extended types => [qw(compile Num NonEmptyStr Str PositiveInt ArrayRef)];
use List::Util 'sum';
# the distinction between `param` and `field` makes it easier to
# see which are available to `new`
param _name => ( isa => NonEmptyStr, init_arg => 'name' );
param title => ( isa => Str, required => 0 );
# forbidden in the constructor
field created => ( isa => PositiveInt, default => sub {time} );
sub name ($self) {
my $title = $self->title;
my $name = $self->_name;
return $title ? "$title $name" : $name;
}
sub add ( $self, $args ) {
state $check = compile( ArrayRef [ Num, 1 ] ); # at least one number
($args) = $check->($args);
return sum( $args->@* );
}
sub warnit ($self) {
carp("this is a warning");
}
}
DESCRIPTION
This module is BETA code. It's feature-complete for release and has no
known bugs. We believe it's ready for production, but make no promises.
This is a quick overview. See MooseX::Extended::Manual::Tutorial for
more information.
This class attempts to create a safer version of Moose that defaults to
read-only attributes and is easier to read and write.
It tries to bring some of the lessons learned from the Corinna project
<https://github.com/Ovid/Cor>, while acknowledging that you can't always
get what you want (such as true encapsulation and true methods).
This:
package My::Class {
use MooseX::Extended;
... your code here
}
Is sort of the equivalent to:
package My::Class {
use v5.20.0;
use Moose;
use MooseX::StrictConstructor;
use feature qw( signatures postderef postderef_qq);
no warnings qw( experimental::signatures experimental::postderef );
use namespace::autoclean;
use Carp;
use mro 'c3';
... your code here
__PACKAGE__->meta->make_immutable;
}
1;
It also exports two functions which are similar to Moose "has": "param"
and "field".
A "param" is a required parameter (defaults may be used). A "field" is
not intended to be passed to the constructor.
Note that the "has" function is still available, even if it's not
needed.
Also, while your author likes the postfix block syntax, it's not
required. You can even safely inline multiple packages in the same file:
package My::Point;
use MooseX::Extended types => [qw/Num/];
param [ 'x', 'y' ] => ( isa => Num );
package My::Point::Mutable;
use MooseX::Extended;
extends 'My::Point';
param [ '+x', '+y' ] => ( writer => 1, clearer => 1, default => 0 );
sub invert ($self) {
my ( $x, $y ) = ( $self->x, $self->y );
$self->set_x($y);
$self->set_y($x);
}
# MooseX::Extended will cause this to return true, even if we try to return
# false
0;
CONFIGURATION
You may pass an import list to MooseX::Extended.
use MooseX::Extended
excludes => [qw/StrictConstructor carp/], # I don't want these features
types => [qw/compile PositiveInt HashRef/]; # I want these type tools
"types"
Allows you to import any types provided by MooseX::Extended::Types.
This:
use MooseX::Extended::Role types => [qw/compile PositiveInt HashRef/];
Is identical to this:
use MooseX::Extended::Role;
use MooseX::Extended::Types qw( compile PositiveInt HashRef );
"excludes"
You may find some features to be annoying, or even cause potential bugs
(e.g., if you have a "croak" method, our importing of "Carp::croak" will
be a problem. You can exclude the following:
* "StrictConstructor"
use MooseX::Extended excludes => ['StrictConstructor'];
Excluding this will no longer import "MooseX::StrictConstructor".
* "autoclean"
use MooseX::Extended excludes => ['autoclean'];
Excluding this will no longer import "namespace::autoclean".
* "c3"
use MooseX::Extended excludes => ['c3'];
Excluding this will no longer apply the C3 mro.
* "carp"
use MooseX::Extended excludes => ['carp'];
Excluding this will no longer import "Carp::croak" and "Carp::carp".
* "immutable"
use MooseX::Extended excludes => ['immutable'];
Excluding this will no longer make your class immutable.
* "true"
use MooseX::Extended excludes => ['true'];
Excluding this will require your module to end in a true value.
* "param"
use MooseX::Extended excludes => ['param'];
Excluding this will make the "param" function unavailable.
* "field"
use MooseX::Extended excludes => ['field'];
Excluding this will make the "field" function unavailable.
"includes"
Some experimental features are useful, but might not be quite what you
want.
By default, MooseX::Extended tries to be relatively conservative.
However, you might want to turn it up to 11. There are optional,
EXPERIMENTAL features you can use for this. They're turned by the
"includes" flag.
* "multi"
use MooseX::Extended includes => [qw/multi/];
multi sub foo ($self, $x) { ... }
multi sub foo ($self, $x, $y ) { ... }
Allows you to redeclare a method (or subroutine) and the dispatch
will use the number of arguments to determine which subroutine to
use. Note that "slurpy" arguments such as arrays or hashes will take
precedence over scalars:
multi sub foo ($self, @x) { ... }
multi sub foo ($self, $x) { ... } # will never be called
Thus, the following probably doesn't do what you want.
package Foo {
use MooseX::Extended includes => [qw/multi/];
multi sub foo ($self, @bar) { return '@bar' }
multi sub foo ($self, $bar) { return '$bar' }
}
say +Foo->new->foo(1);
say +Foo->new->foo(1,2,3);
Both of the above will print the string @bar. The second definition
of "foo" is effectively lost.
Only available on Perl v5.26.0 or higher. Requires
Syntax::Keyword::MultiSub.
* "async"
package My::Thing {
use MooseX::Extended
types => [qw/Str/],
includes => ['async'];
use IO::Async::Loop;
field output => ( is => 'rw', isa => Str, default => '' );
async sub doit ( $self, @list ) {
my $loop = IO::Async::Loop->new;
$self->output('> ');
foreach my $item (@list) {
await $loop->delay_future( after => 0.01 );
$self->output( $self->output . "$item " );
}
}
}
Allows you to write asynchronous code with "async" and "await".
Only available on Perl v5.26.0 or higher. Requires
Future::AsyncAwait.
REDUCING BOILERPLATE
Let's say you've settled on the following feature set:
use MooseX::Extended
excludes => [qw/StrictConstructor carp/],
includes => [qw/multi/];
And you keep typing that over and over. We've removed a lot of
boilerplate, but we've added different boilerplate. Instead, just create
"My::Custom::Moose" and "use My::Custom::Moose;". See
MooseX::Extended::Custom for details.
IMMUTABILITY
Making Your Class Immutable
You no longer need to end your Moose classes with:
__PACKAGE__->meta->make_immutable;
That prevents further changes to the class and provides some
optimizations to make the code run much faster. However, it's somewhat
annoying to type. We do this for you, via B::Hooks::AtRuntime. You no
longer need to do this yourself.
Making Your Instance Immutable
By default, attributes defined via "param" and "field" are read-only.
However, if they contain a reference, you can fetch the reference,
mutate it, and now everyone with a copy of that reference has mutated
state.
To handle that, we offer a new "clone => $clone_type" pair for
attributes.
See the MooseX::Extended::Manual::Cloning documentation.
OBJECT CONSTRUCTION
Object construction for MooseX::Extended is identical to Moose because
MooseX::Extended *is* Moose, so no changes are needed. However, in
addition to "has", we also provide "param" and "field" attributes, both
of which are "is => 'ro'" by default.
The "param" is *required*, whether by passing it to the constructor, or
using "default" or "builder".
The "field" is *forbidden* in the constructor and is lazy if it has a
builder, because that builder is often dependent on attributes set in
the constructor (and why call it if it's not used?).
Here's a short example:
package Class::Name {
use MooseX::Extended types => [qw(compile Num NonEmptyStr Str)];
# these default to 'ro' (but you can override that) and are required
param _name => ( isa => NonEmptyStr, init_arg => 'name' );
param title => ( isa => Str, required => 0 );
# fields must never be passed to the constructor
# note that ->title and ->name are guaranteed to be set before
# this because fields are lazy by default
field name => (
isa => NonEmptyStr,
default => sub ($self) {
my $title = $self->title;
my $name = $self->_name;
return $title ? "$title $name" : $name;
},
);
}
See MooseX::Extended::Manual::Construction for a full explanation.
ATTRIBUTE SHORTCUTS
When using "field" or "param", we have some attribute shortcuts:
param name => (
isa => NonEmptyStr,
writer => 1, # set_name
reader => 1, # get_name
predicate => 1, # has_name
clearer => 1, # clear_name
builder => 1, # _build_name
);
sub _build_name ($self) {
...
}
You can also do this:
param name ( isa => NonEmptyStr, builder => sub {...} );
That's the same as:
param name ( isa => NonEmptyStr, builder => '_build_name' );
sub _build_name {...}
See MooseX::Extended::Manual::Shortcuts for a full explanation.
INVALID ATTRIBUTE DEFINITIONS
The following Moose code will print "WhoAmI". However, the second
attribute name is clearly invalid.
package Some::Class {
use Moose;
has name => ( is => 'ro' );
has '-bad' => ( is => 'ro' );
}
my $object = Some::Class->new( name => 'WhoAmI' );
say $object->name;
"MooseX::Extended" will throw a
Moose::Exception::InvalidAttributeDefinition exception if it encounters
an illegal method name for an attribute.
This also applies to various attributes which allow method names, such
as "clone", "builder", "clearer", "writer", "reader", and "predicate".
Trying to pass a defined "init_arg" to "field" will also throw this
exception, unless the init_arg begins with an underscore. (It is
sometimes useful to be able to define an "init_arg" for unit testing.)
BUGS AND LIMITATIONS
If the MooseX::Extended classes are loaded via *stringy* eval, "true" is
not loaded, nor is your class made immutable. This is because there were
intermittant errors (maybe 1 out of 5 times) being thrown. Removing
these features under stringy eval solves this. See this github ticket
for more infomration <https://github.com/Ovid/moosex-extreme/pull/34>.
MANUAL
* MooseX::Extended::Manual::Tutorial
* MooseX::Extended::Manual::Overview
* MooseX::Extended::Manual::Construction
* MooseX::Extended::Manual::Shortcuts
* MooseX::Extended::Manual::Cloning
RELATED MODULES
* MooseX::Extended::Types is included in the distribution.
This provides core types for you.
* MooseX::Extended::Role is included in the distribution.
"MooseX::Extended", but for roles.
TODO
Some of this may just be wishful thinking. Some of this would be
interesting if others would like to collaborate.
Configurable Types
We provide "MooseX::Extended::Types" for convenience, along with the
"declare" function. We should write up (and test) examples of extending
it.
"BEGIN::Lift"
This idea maybe belongs in "MooseX::Extended::OverKill", but ...
Quite often you see things like this:
BEGIN { extends 'Some::Parent' }
Or this:
sub serial_number; # required by a role, must be compile-time
has serial_number => ( ... );
In fact, there are a variety of Moose functions which would work better
if they ran at compile-time instead of runtime, making them look a touch
more like native functions. My various attempts at solving this have
failed, but I confess I didn't try too hard.
NOTES
There are a few things you might be interested to know about this module
when evaluating it.
Most of this is written with bog-standard Moose, so there's nothing
terribly weird inside, but you may wish to note that we use
B::Hooks::AtRuntime and true. They seem sane, but *caveat emptor*.
This module was originally released on github as "MooseX::Extreme", but
enough people pointed out that it was not extreme at all. That's why the
repository is <https://github.com/Ovid/moosex-extreme/>.
SEE ALSO
* Corinna <https://github.com/Ovid/Cor>
The RFC of the new version of OOP planned for the Perl core.
* MooseX::Modern <https://metacpan.org/pod/MooseX::Modern>
MooseX::Modern - Precision classes for Modern Perl
* Zydeco <https://metacpan.org/pod/Zydeco>
Zydeco - Jazz up your Perl
* Dios <https://metacpan.org/pod/Dios>
Dios - Declarative Inside-Out Syntax
* MooseX::AttributeShortcuts
<https://metacpan.org/pod/MooseX::AttributeShortcuts>
MooseX::AttributeShortcuts - Shorthand for common attribute options
AUTHOR
Curtis "Ovid" Poe <curtis.poe@gmail.com>
COPYRIGHT AND LICENSE
This software is Copyright (c) 2022 by Curtis "Ovid" Poe.
This is free software, licensed under:
The Artistic License 2.0 (GPL Compatible)