Provided by: libbread-board-perl_0.32-1_all 
NAME
Bread::Board - A solderless way to wire up your application components
VERSION
version 0.32
SYNOPSIS
use Bread::Board;
my $c = container 'MyApp' => as {
service 'log_file_name' => "logfile.log";
service 'logger' => (
class => 'FileLogger',
lifecycle => 'Singleton',
dependencies => [ 'log_file_name' ],
]
);
container 'Database' => as {
service 'dsn' => "dbi:SQLite:dbname=my-app.db";
service 'username' => "user234";
service 'password' => "****";
service 'dbh' => (
block => sub {
my $s = shift;
require DBI;
DBI->connect(
$s->param('dsn'),
$s->param('username'),
$s->param('password'),
) || die "Could not connect";
},
dependencies => [ 'dsn', 'username', 'password' ]
);
};
service 'application' => (
class => 'MyApplication',
dependencies => {
logger => 'logger',
dbh => 'Database/dbh',
}
);
};
no Bread::Board; # removes keywords
# get an instance of MyApplication
# from the container
my $app = $c->resolve( service => 'application' );
# now user your MyApplication
# as you normally would ...
$app->run;
DESCRIPTION
Bread::Board is an inversion of control framework with a focus on dependency injection and
lifecycle management. It's goal is to help you write more decoupled objects and components
by removing the need for you to manually wire those objects/components together.
Want to know more? See the Bread::Board::Manual.
+-----------------------------------------+
| A B C D E F G H I J |
|-----------------------------------------|
| o o | 1 o-o-o-o-o v o-o-o-o-o 1 | o o |
| o o | 2 o-o-o-o-o o-o-o-o-o 2 | o o |
| o o | 3 o-o-o-o-o o-o-o-o-o 3 | o o |
| o o | 4 o-o-o-o-o o-o-o-o-o 4 | o o |
| o o | 5 o-o-o-o-o o-o-o-o-o 5 | o o |
| | 6 o-o-o-o-o o-o-o-o-o 6 | |
| o o | 7 o-o-o-o-o o-o-o-o-o 7 | o o |
| o o | 8 o-o-o-o-o o-o-o-o-o 8 | o o |
| o o | 9 o-o-o-o-o o-o-o-o-o 9 | o o |
| o o | 10 o-o-o-o-o o-o-o-o-o 10 | o o |
| o o | 11 o-o-o-o-o o-o-o-o-o 11 | o o |
| | 12 o-o-o-o-o o-o-o-o-o 12 | |
| o o | 13 o-o-o-o-o o-o-o-o-o 13 | o o |
| o o | 14 o-o-o-o-o o-o-o-o-o 14 | o o |
| o o | 15 o-o-o-o-o o-o-o-o-o 15 | o o |
| o o | 16 o-o-o-o-o o-o-o-o-o 16 | o o |
| o o | 17 o-o-o-o-o o-o-o-o-o 17 | o o |
| | 18 o-o-o-o-o o-o-o-o-o 18 | |
| o o | 19 o-o-o-o-o o-o-o-o-o 19 | o o |
| o o | 20 o-o-o-o-o o-o-o-o-o 20 | o o |
| o o | 21 o-o-o-o-o o-o-o-o-o 21 | o o |
| o o | 22 o-o-o-o-o o-o-o-o-o 22 | o o |
| o o | 22 o-o-o-o-o o-o-o-o-o 22 | o o |
| | 23 o-o-o-o-o o-o-o-o-o 23 | |
| o o | 24 o-o-o-o-o o-o-o-o-o 24 | o o |
| o o | 25 o-o-o-o-o o-o-o-o-o 25 | o o |
| o o | 26 o-o-o-o-o o-o-o-o-o 26 | o o |
| o o | 27 o-o-o-o-o o-o-o-o-o 27 | o o |
| o o | 28 o-o-o-o-o ^ o-o-o-o-o 28 | o o |
+-----------------------------------------+
Loading this package will automatically load the rest of the packages needed by your
Bread::Board configuration.
EXPORTED FUNCTIONS
The functions of this package provide syntactic sugar to help you build your Bread::Board
configuration. You can build such a configuration by constructing the objects manually
instead, but your code may be more difficult to understand.
container ($name, &body)
This function constructs and returns an instance of Bread::Board::Container. The
(optional) &body block may be used to add services or sub-containers within the newly
constructed container. Usually, the block is not passed directly, but passed using the
"as" function.
For example,
container 'MyWebApp' => as {
service my_dispatcher => (
class => 'MyWebApp::Dispatcher',
);
};
If $name starts with '+', and the container is being declared inside another
container, then this declaration will instead extend an existing container with the
name $name (without the '+').
container ($container_instance, &body)
In many cases, subclassing Bread::Board::Container is the easiest route to getting
access to this framework. You can do this and still get all the benefits of the
syntactic sugar for configuring that class by passing an instance of your container
subclass to "container".
You could, for example, configure your container inside the "BUILD" method of your
class:
package MyWebApp;
use Moose;
extends 'Bread::Board::Container';
sub BUILD {
my $self = shift;
container $self => as {
service dbh => ( ... );
};
}
container ($name, [ @parameters ], &body)
A third way of using the "container" function is to build a parameterized container.
These are useful as a way of providing a placeholder for parts of the configuration
that may be provided later. You may not use an instance object in place of the $name
in this case.
For more detail on how you might use parameterized containers, see "Parameterized
Containers" in Bread::Board::Manual::Concepts::Advanced.
as (&body)
This is just a replacement for the "sub" keyword that is easier to read when defining
containers.
service ($name, $literal | %service_description)
Within the "as" blocks for your containers, you may construct services using the
"service" function. This can construct several different kinds of services based upon
how it is called.
To build a literal service (a Bread::Board::Literal object), just specify a scalar
value or reference you want to use as the literal value:
# In case you need to adjust the gravitational constant of the Universe
service gravitational_constant => 6.673E-11;
To build a service using one of the injection services, just fill in all the details
required to use that sort of injection:
service search_service => (
class => 'MyApp::Search',
block => sub {
my $s = shift;
MyApp::Search->new($s->param('url'), $s->param('type'));
},
dependencies => {
url => 'search_url',
},
parameters => {
type => { isa => 'Str', default => 'text' },
},
);
The type of injection performed depends on the parameters used. You may use the
"service_class" parameter to pick a specific injector class. For instance, this is
useful if you need to use Bread::Board::SetterInjection or have defined a custom
injection service. If you specify a "block", block injection will be performed using
Bread::Board::BlockInjection. If neither of these is present, constructor injection
will be used with Bread::Board::ConstructorInjection (and you must provide the "class"
option).
The "dependencies" parameter takes a hashref of dependency names mapped to
Bread::Board::Dependency objects, but there are several coercions and sugar functions
available to make specifying dependencies as easy as possible. The simplest case is
when the names of the services you're depending on are the same as the names that the
service you're defining will be accessing them with. In this case, you can just
specify an arrayref of service names:
service foo => (
dependencies => [ 'bar', 'baz' ],
# ...
);
If you need to use a different name, you can specify the dependencies as a hashref
instead:
service foo => (
dependencies => {
dbh => 'foo_dbh',
},
# ...
);
You can also specify parameters when depending on a parameterized service:
service foo => (
dependencies => [
{ bar => { bar_param => 1 } },
'baz',
],
# ...
);
Finally, services themselves can also be specified as dependencies, in which case they
will just be resolved directly:
service foo => (
dependencies => {
dsn => Bread::Board::Literal->new(
name => 'dsn',
value => 'dbi:mysql:mydb',
),
},
# ...
);
As a special case, an arrayref of dependencies will be interpreted as a service which
returns an arrayref containing the resolved values of those dependencies:
service foo => (
dependencies => {
# items will resolve to [ $bar_service->get, $baz_service->get ]
items => [
'bar',
Bread::Board::Literal->new(name => 'baz', value => 'BAZ'),
],
},
# ...
);
If the $name starts with a '+', the service definition will instead extend an existing
service with the given $name (without the '+'). This works similarly to the "has
'+foo'" syntax in Moose. It is most useful when defining a container class where the
container is built up in "BUILD" methods, as each class in the inheritance hierarchy
can modify services defined in superclasses. The "dependencies" and "parameters"
options will be merged with the existing values, rather than overridden. Note that
literal services can't be extended, because there's nothing to extend. You can still
override them entirely by declaring the service name without a leading '+'.
depends_on ($service_path)
The "depends_on" function creates a Bread::Board::Dependency object for the named
$service_path and returns it.
wire_names (@service_names)
This function is just a shortcut for passing a hash reference of dependencies into the
service. It is not typically needed, since Bread::Board can usually understand what
you mean - these declarations are all equivalent:
service foo => (
class => 'Pity::TheFoo',
dependencies => {
foo => depends_on('foo'),
bar => depends_on('bar'),
baz => depends_on('baz'),
},
);
service foo => (
class => 'Pity::TheFoo',
dependencies => wire_names(qw( foo bar baz )),
);
service foo => (
class => 'Pity::TheFoo',
dependencies => {
foo => 'foo',
bar => 'bar',
baz => 'baz',
},
);
service foo => (
class => 'Pity::TheFoo',
dependencies => [ qw(foo bar baz ) ],
);
typemap ($type, $service | $service_path)
This creates a type mapping for the named type. Typically, it is paired with the
"infer" call like so:
typemap 'MyApp::Model::UserAccount' => infer;
For more details on what type mapping is and how it works, see
Bread::Board::Manual::Concepts::Typemap.
infer (?%hints)
This is used with "typemap" to help create the typemap inference. It can be used with
no arguments to do everything automatically. However, in some cases, you may want to
pass a service instance as the argument or a hash of service arguments to change how
the type map works. For example, if your type needs to be constructed using a setter
injection, you can use an inference similar to this:
typemap 'MyApp::Model::UserPassword' => infer(
service_class => 'Bread::Board::SetterInjection',
);
For more details on what type mapping is and how it works, see
Bread::Board::Manual::Concepts::Typemap.
include ($file)
This is a shortcut for loading a Bread::Board configuration from another file.
include "filename.pl";
The above is pretty much identical to running:
do "filename.pl";
However, you might find it more readable to use "include".
alias ($service_name, $service_path, %service_description)
This helper allows for the creation of service aliases, which allows you to define a
service in one place and then reuse that service with a different name somewhere else.
This is sort of like a symbolic link for services. Aliases will be resolved
recursively, so an alias can alias an alias.
For example,
service file_logger => (
class => 'MyApp::Logger::File',
);
alias my_logger => 'file_logger';
OTHER FUNCTIONS
These are not exported, but might be helpful to you.
set_root_container ($container)
You may use this to set a top-level root container for all container definitions.
For example,
my $app = container MyApp => as { ... };
Bread::Board::set_root_container($app);
my $config = container Config => as { ... };
Here the $config container would be created as a sub-container of $app.
ACKNOWLEDGEMENTS
Thanks to Daisuke Maki for his contributions and for really pushing the development of
this module along.
Chuck "sprongie" Adams, for testing/using early (pre-release) versions of this module, and
some good suggestions for naming it.
Matt "mst" Trout, for finally coming up with the best name for this module.
ARTICLES
Bread::Board is the right tool for this job
<http://domm.plix.at/perl/2013_04_bread_board_is_the_right_rool_for_this_job.html> Thomas
Klausner showing a use-case for Bread::Board.
SEE ALSO
Bread::Board::Declare
This provides more powerful syntax for writing Bread::Board container classes.
IOC Bread::Board is basically my re-write of IOC.
<http://en.wikipedia.org/wiki/Breadboard>
BUGS
All complex software has bugs lurking in it, and this module is no exception. If you find
a bug please either email me, or add the bug to Github Issues.
AUTHOR
Stevan Little <stevan@iinteractive.com>
COPYRIGHT AND LICENSE
This software is copyright (c) 2014 by Infinity Interactive.
This is free software; you can redistribute it and/or modify it under the same terms as
the Perl 5 programming language system itself.