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       Bread::Board::Manual::Concepts::Typemap - An overview of	the
       typemapping feature

       version 0.37

       A new (read: experimental) feature of Bread::Board is typemapped
       services.  These	are services which are mapped to a particular type
       rather then just	a name.	This feature has the potential to make
       obsolete	a large	amount of the Bread::Board configuration by simply
       asking Bread::Board to figure things out	on its own. Here is a small
       example of how this works.

	 # define the classes making sure
	 # to specify required items and
	 # their types

	     package Stapler;
	     use Moose;

	     package Desk;
	     use Moose;

	     package Chair;
	     use Moose;

	     package Cubicle;
	     use Moose;

	     has 'desk'	 => ( is => 'ro', isa => 'Desk',  required => 1	);
	     has 'chair' => ( is => 'ro', isa => 'Chair', required => 1	);

	     package Employee;
	     use Moose;

	     has [ 'first_name', 'last_name' ] => (
		 is	  => 'ro',
		 isa	  => 'Str',
		 required => 1,

	     has 'stapler' => (	is => 'rw', isa	=> 'Stapler', predicate	=> 'has_stapler' );

	     has 'work_area' =>	( is =>	'ro', isa => 'Cubicle',	required => 1 );

	 # now create the container, and
	 # map the Employee type and ask
	 # Bread::Board	to infer all the
	 # other relationships

	 my $c = container 'Initech' =>	as {
	     typemap 'Employee'	=> infer;

	 # now you can create new Employee objects
	 # by calling ->resolve	with the type and
	 # supplying the required parameters (see
	 # below for details).

	 my $micheal = $c->resolve(
	     type	=> 'Employee',
	     parameters	=> {
		 first_name => 'Micheal',
		 last_name  => 'Bolton'

	 my $cube = $micheal->work_area; # this	will be	a Cubicle object
	 $cube->desk;  # this will be a	Desk object
	 $cube->chair; # this will be a	Chair object

	 $micheal->has_stapler;	# this is false

	 # We can create another Employee object
	 # and this time we pass in the	optional
	 # parameter for the non-required 'stapler'
	 # attribute

	 my $milton = $c->resolve(
	     type	=> 'Employee',
	     parameters	=> {
		 first_name => 'Milton',
		 last_name  => 'Waddams',
		 stapler    => Stapler->new

	 $milton->has_stapler; # this is true

       In the above example, we	created	a number of Moose classes that had
       specific	required relationships.	When we	called "infer" for the
       Employee	object,	Bread::Board figured out those relationships and set
       up dependencies and parameters accordingly.

       For the "work_area" object, we saw the Cubicle type and then basically
       called "infer" on the Cubicle object. We	then saw the Desk and Chair
       objects and called "infer" on those as well.  The result	of this
       recursive inference was that the	Employee, Cubicle, Desk	and Chair
       relationships were modeled in Bread::Board as dependent services.

       Bread::Board also took it one step further.

       We were able to resolve the Cubicle, Desk and Chair types automatically
       because they were already defined by Moose as subtypes of the Object
       type. We	knew that it could introspect those classes and	get more
       information. However, this was not the case with	the first_name and
       last_name attributes of the Employee object.  In	that case, we
       determined that we couldn't resolve those objects and (because it was a
       top-level inference) instead turned them	into required parameters for
       the inferred Employee service.

       And lastly, with	a top-level inference (not one caused by recursion)
       Bread::Board will also look at all the remaining	non-required
       attributes and turn them	into optional parameters. In this case we have
       a "stapler" attribute that is not required and so is listed as an
       optional	parameter, meaning that	it is not required, but	still subject
       to type checking.

       This example should give	a good basic overview of this feature and more
       details can be found in the test	suite (t/07*.t). These show examples
       of how to typemap roles to concrete classes and how to supply hints to
       "infer" to help Bread::Board figure out specific	details.

       As I mentioned above, this feature should be considered experimental
       and we are still	working	out details and	writing	tests for it. Any
       contributions are welcome.

       Stevan Little <>

       Please report any bugs or feature requests on the bugtracker website

       When submitting a bug or	request, please	include	a test-file or a patch
       to an existing test-file	that illustrates the bug or desired feature.

       This software is	copyright (c) 2019, 2017, 2016,	2015, 2014, 2013,
       2011, 2009 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.

perl v5.32.1			  20Bread::Board::Manual::Concepts::Typemap(3)


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