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.\" ========================================================================
.\"
.IX Title "Bread::Board::Service::WithDependencies 3pm"
.TH Bread::Board::Service::WithDependencies 3pm "2022-12-12" "perl v5.36.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH "NAME"
Bread::Board::Service::WithDependencies \- Services with dependencies
.SH "VERSION"
.IX Header "VERSION"
version 0.37
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This is a sub-role of Bread::Board::Service, for services with
dependencies. It provides the mechanism to recursively resolve
dependencies.
.SH "ATTRIBUTES"
.IX Header "ATTRIBUTES"
.ie n .SS """dependencies"""
.el .SS "\f(CWdependencies\fP"
.IX Subsection "dependencies"
Hashref, constrained by \f(CW\*(C`Bread::Board::Service::Dependencies\*(C'\fR. Values must be instances of Bread::Board::Dependency, but can
be coerced from various other types, see the type's
docs.
.SH "METHODS"
.IX Header "METHODS"
.ie n .SS """add_dependency"""
.el .SS "\f(CWadd_dependency\fP"
.IX Subsection "add_dependency"
.Vb 1
\&  $service\->add_dependency(name=>$dep);
.Ve
.PP
Adds a new dependency.
.ie n .SS """get_dependency"""
.el .SS "\f(CWget_dependency\fP"
.IX Subsection "get_dependency"
.Vb 1
\&  my $dep = $service\->get_dependency(\*(Aqname\*(Aq);
.Ve
.PP
Gets a dependency by name.
.ie n .SS """has_dependency"""
.el .SS "\f(CWhas_dependency\fP"
.IX Subsection "has_dependency"
.Vb 1
\&  if ($service\->has_dependency(\*(Aqname\*(Aq)) { ... }
.Ve
.PP
Returns true if this service has a dependency with the given name.
.ie n .SS """has_dependencies"""
.el .SS "\f(CWhas_dependencies\fP"
.IX Subsection "has_dependencies"
.Vb 1
\&  if ($service\->has_dependencies) { ... }
.Ve
.PP
Returns true if this service has any dependency.
.ie n .SS """get_all_dependencies"""
.el .SS "\f(CWget_all_dependencies\fP"
.IX Subsection "get_all_dependencies"
.Vb 1
\&  my %deps = $service\->get_all_dependencies;
.Ve
.PP
Returns all the dependencies for this service, as a key-value list.
.ie n .SS """init_params"""
.el .SS "\f(CWinit_params\fP"
.IX Subsection "init_params"
Builder for the service parameters, augmented to inject all the
resolved dependencies into the \f(CW\*(C`params\*(C'\fR attribute, so that \f(CW\*(C`get\*(C'\fR
can use them.
.ie n .SS """get"""
.el .SS "\f(CWget\fP"
.IX Subsection "get"
\&\fIAfter\fR the \f(CW\*(C`get\*(C'\fR method, the \f(CW\*(C`params\*(C'\fR attribute is cleared, to
make sure that dependencies will be resolved again on the next call (of
course, if the service is using a singleton
lifecycle, the whole \*(L"getting\*(R"
only happens once).
.ie n .SS """resolve_dependencies"""
.el .SS "\f(CWresolve_dependencies\fP"
.IX Subsection "resolve_dependencies"
.Vb 1
\&  my %name_object_map = $self\->resolve_dependencies;
.Ve
.PP
For each element of \*(L"dependencies\*(R", calls its \f(CW\*(C`service\*(C'\fR method to retrieve the
service we're dependent on, then tries to instantiate the value of the
service. This can happen in a few different ways:
.IP "the service is not locked, and does not require any parameter" 4
.IX Item "the service is not locked, and does not require any parameter"
just call \f(CW\*(C`get\*(C'\fR on it
.IP "the service is not locked, requires parameters, but the dependency has values for them" 4
.IX Item "the service is not locked, requires parameters, but the dependency has values for them"
call \f(CW\*(C`$service\->get(%{$dependency\->service_params})\*(C'\fR
.IP "the service is not locked, requires parameters, and we don't have values for them" 4
.IX Item "the service is not locked, requires parameters, and we don't have values for them"
we can't instantiate anything at this point, so we use a
Bread::Board::Service::Deferred::Thunk instance, on which you can
call the \f(CW\*(C`inflate\*(C'\fR method, passing it all the needed parameters, to
get the actual instance
.IP "the service is locked" 4
.IX Item "the service is locked"
we return a Bread::Board::Service::Deferred that will proxy to the
instance that the service will eventually return; yes, this means that
in many cases circular dependencies can be resolved, at the cost of a
proxy object
.SH "AUTHOR"
.IX Header "AUTHOR"
Stevan Little <stevan@iinteractive.com>
.SH "BUGS"
.IX Header "BUGS"
Please report any bugs or feature requests on the bugtracker website
https://github.com/stevan/BreadBoard/issues
.PP
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.
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
This software is copyright (c) 2019, 2017, 2016, 2015, 2014, 2013, 2011, 2009 by Infinity Interactive.
.PP
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.