NAME
MooX::ObjectBuilder - lazy construction of objects from extra init args
SYNOPSIS
package Person {
use Moo;
has name => (is => "ro");
has title => (is => "ro");
}
package Organization {
use Moo;
use MooX::ObjectBuilder;
has name => (is => "ro");
has boss => (
is => make_builder(
"Person" => (
boss_name => "name",
boss_title => "title",
),
),
);
}
my $org = Organization->new(
name => "Catholic Church",
boss_name => "Francis",
boss_title => "Pope",
);
use Data::Dumper;
print Dumper( $org->boss );
DESCRIPTION
This module exports a function `make_builder` which can be used to
generate lazy builders suitable for Moo attributes. The import procedure
also performs some setup operations on the caller class necessary for
`make_builder` to work correctly.
Functions
`make_builder( $class|$coderef, \%args|\@args|%args )`
The `make_builder` function conceptually takes two arguments, though
the second one (which is normally a hashref or arrayref) may be passed
as a flattened hash.
The %args hash is a mapping of argument names where keys are names in
the "aggregating" or "container" class (i.e. "Organization" in the
"SYNOPSIS") and values are names in the "aggregated" or "contained"
class (i.e. "Person" in the "SYNOPSIS").
If `\@args` is provided instead, this is expanded into a hash as
follows:
my %args = map { $_ => $_ } @args;
The builder returned by this function will accept arguments from the
aggregating class and map them into arguments for the aggregated
class. The builder will then construct an instance of $class passing
it a hashref of arguments. If $coderef has been provided instead of a
class name, this will be called with the hashref of arguments instead.
The `make_builder` function behaves differently in scalar and list
context. In list context, it returns a three item list. The first two
items are the strings "lazy" and "builder"; the third item is the
builder coderef described above. In scalar context, only the coderef
is returned. Thus the following two examples work equivalently:
# Scalar context
my $builder = make_builder($class, {...});
has attr => (
is => "lazy",
builder => $builder,
);
# List context
has attr => (
is => make_builder($class, {...}),
);
Class Setup
On import, this module installs a sub called `BUILD` into your class. If
your class already has a sub with this name, it will be wrapped.
The point of this sub is to capture argument passed to the aggregating
class' constructor, to enable them to be later forwarded to the aggregated
class.
See also: "BUILD" in Moo.
Using MooX::ObjectBuilder with Moose and Mouse
It is possible to use `make_builder` in scalar context with Moose and
Mouse classes:
has attr => (
is => "ro",
lazy => 1,
default => scalar make_builder($class, {...}),
);
MooseX::ConstructInstance
If your object does the MooseX::ConstructInstance role, then this module
will automatically do the right thing and delegate to that for the actual
object construction.
BUGS
Please report any bugs to
<http://rt.cpan.org/Dist/Display.html?Queue=MooX-ObjectBuilder>.
SEE ALSO
Moo, Moose, Mouse.
MooseX::ConstructInstance.
MooX::LazyRequire, MooseX::LazyRequire, MooseX::LazyCoercion, etc.
AUTHOR
Toby Inkster <tobyink@cpan.org>.
CREDITS
Most of the test suite was written by Torbjørn Lindahl (cpan:TORBJORN).
Various advice was given by Graham Knop (cpan:HAARG) and Matt S Trout
(cpan:MSTROUT).
COPYRIGHT AND LICENCE
This software is copyright (c) 2014 by Toby Inkster.
This is free software; you can redistribute it and/or modify it under the
same terms as the Perl 5 programming language system itself.
DISCLAIMER OF WARRANTIES
THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.