NAME
Moo - Minimalist Object Orientation (with Moose compatiblity)
SYNOPSIS
package Cat::Food;
use Moo;
use Sub::Quote;
sub feed_lion {
my $self = shift;
my $amount = shift || 1;
$self->pounds( $self->pounds - $amount );
}
has taste => (
is => 'ro',
);
has brand => (
is => 'ro',
isa => sub {
die "Only SWEET-TREATZ supported!" unless $_[0] eq 'SWEET-TREATZ'
},
);
has pounds => (
is => 'rw',
isa => quote_sub q{ die "$_[0] is too much cat food!" unless $_[0] < 15 },
);
1;
and else where
my $full = Cat::Food->new(
taste => 'DELICIOUS.',
brand => 'SWEET-TREATZ',
pounds => 10,
);
$full->feed_lion;
say $full->pounds;
DESCRIPTION
This module is an extremely light-weight, high-performance Moose
replacement. It also avoids depending on any XS modules to allow simple
deployments. The name "Moo" is based on the idea that it provides almost
-but not quite- two thirds of Moose.
Unlike "Mouse" this module does not aim at full Moose compatibility. See
"INCOMPATIBILITIES" for more details.
WHY MOO EXISTS
If you want a full object system with a rich Metaprotocol, Moose is
already wonderful.
I've tried several times to use Mouse but it's 3x the size of Moo and
takes longer to load than most of my Moo based CGI scripts take to run.
If you don't want Moose, you don't want "less metaprotocol" like Mouse,
you want "as little as possible" - which means "no metaprotocol", which
is what Moo provides.
By Moo 1.0 I intend to have Moo's equivalent of Any::Moose built in - if
Moose gets loaded, any Moo class or role will act as a Moose equivalent
if treated as such.
Hence - Moo exists as its name - Minimal Object Orientation - with a
pledge to make it smooth to upgrade to Moose when you need more than
minimal features.
IMPORTED METHODS
new
Foo::Bar->new( attr1 => 3 );
or
Foo::Bar->new({ attr1 => 3 });
BUILDARGS
This feature from Moose is not yet supported.
BUILDALL
Don't override (or probably even call) this method. Instead, you can
define a "BUILD" method on your class and the constructor will
automatically call the "BUILD" method from parent down to child after
the object has been instantiated. Typically this is used for object
validation or possibly logging.
does
if ($foo->does('Some::Role1')) {
...
}
Returns true if the object composes in the passed role.
IMPORTED SUBROUTINES
extends
extends 'Parent::Class';
Declares base class. Multiple superclasses can be passed for multiple
inheritance (but please use roles instead).
Calling extends more than once will REPLACE your superclasses, not add
to them like 'use base' would.
with
with 'Some::Role1';
with 'Some::Role2';
Composes a Role::Tiny into current class. Only one role may be composed
in at a time to allow the code to remain as simple as possible.
has
has attr => (
is => 'ro',
);
Declares an attribute for the class.
The options for "has" are as follows:
* is
required, must be "ro" or "rw". Unsurprisingly, "ro" generates an
accessor that will not respond to arguments; to be clear: a getter
only. "rw" will create a perlish getter/setter.
* isa
Takes a coderef which is meant to validate the attribute. Unlike Moose
Moo does not include a basic type system, so instead of doing "isa =>
'Num'", one should do
isa => quote_sub q{
die "$_[0] is not a number!" unless looks_like_number $_[0]
},
Sub::Quote aware
* coerce
Takes a coderef which is meant to coerce the attribute. The basic idea
is to do something like the following:
coerce => quote_sub q{
$_[0] + 1 unless $_[0] % 2
},
Coerce does not require "isa" to be defined.
Sub::Quote aware
* trigger
Takes a coderef which will get called any time the attribute is set.
Coderef will be invoked against the object with the new value as an
argument.
Note that Moose also passes the old value, if any; this feature is not
yet supported.
Sub::Quote aware
* default
Takes a coderef which will get called with $self as its only argument
to populate an attribute if no value is supplied to the constructor -
or if the attribute is lazy, when the attribute is first retrieved if
no value has yet been provided.
Note that if your default is fired during new() there is no guarantee
that other attributes have been populated yet so you should not rely
on their existence.
Sub::Quote aware
* predicate
Takes a method name which will return true if an attribute has a
value.
A common example of this would be to call it "has_$foo", implying that
the object has a $foo set.
* builder
Takes a method name which will be called to create the attribute -
functions exactly like default except that instead of calling
$default->($self);
Moo will call
$self->$builder;
* clearer
Takes a method name which will clear the attribute.
* lazy
Boolean. Set this if you want values for the attribute to be grabbed
lazily. This is usually a good idea if you have a "builder" which
requires another attribute to be set.
* required
Boolean. Set this if the attribute must be passed on instantiation.
* weak_ref
Boolean. Set this if you want the reference that the attribute
contains to be weakened; use this when circular references are
possible, which will cause leaks.
* init_arg
Takes the name of the key to look for at instantiation time of the
object. A common use of this is to make an underscored attribute have
a non-underscored initialization name. "undef" means that passing the
value in on instantiation
before
before foo => sub { ... };
See "before method(s) => sub { ... }" in Class::Method::Modifiers for
full documentation.
around
around foo => sub { ... };
See "around method(s) => sub { ... }" in Class::Method::Modifiers for
full documentation.
after
after foo => sub { ... };
See "after method(s) => sub { ... }" in Class::Method::Modifiers for
full documentation.
SUB QUOTE AWARE
"quote_sub" in Sub::Quote allows us to create coderefs that are
"inlineable," giving us a handy, XS-free speed boost. Any option that is
Sub::Quote aware can take advantage of this.
INCOMPATIBILITIES WITH MOOSE
You can only compose one role at a time. If your application is large or
complex enough to warrant complex composition, you wanted Moose.
There is no complex type system. "isa" is verified with a coderef, if
you need complex types, just make a library of coderefs, or better yet,
functions that return quoted subs.
"initializer" is not supported in core since the author considers it to
be a bad idea but may be supported by an extension in future.
There is no meta object. If you need this level of complexity you wanted
Moose - Moo succeeds at being small because it explicitly does not
provide a metaprotocol.
No support for "super", "override", "inner", or "augment" - override can
be handled by around albeit with a little more typing, and the author
considers augment to be a bad idea.
"default" only supports coderefs, because doing otherwise is usually a
mistake anyway.
"lazy_build" is not supported per se, but of course it will work if you
manually set all the options it implies.
"auto_deref" is not supported since the author considers it a bad idea.
"documentation" is not supported since it's a very poor replacement for
POD.
AUTHOR
mst - Matt S. Trout (cpan:MSTROUT) <mst@shadowcat.co.uk>
CONTRIBUTORS
dg - David Leadbeater (cpan:DGL) <dgl@dgl.cx>
frew - Arthur Axel "fREW" Schmidt (cpan:FREW) <frioux@gmail.com>
hobbs - Andrew Rodland (cpan:ARODLAND) <arodland@cpan.org>
jnap - John Napiorkowski (cpan:JJNAPIORK) <jjn1056@yahoo.com>
ribasushi - Peter Rabbitson (cpan:RIBASUSHI) <ribasushi@cpan.org>
chip - Chip Salzenberg (cpan:CHIPS) <chip@pobox.com>
COPYRIGHT
Copyright (c) 2010-2011 the Moo "AUTHOR" and "CONTRIBUTORS" as listed
above.
LICENSE
This library is free software and may be distributed under the same
terms as perl itself.