package Object::Depot; our $VERSION = '0.02'; use strictures 2; =encoding utf8 =head1 NAME Object::Depot - Decouple object instantiation from usage. =head1 SYNOPSIS use Object::Depot; my $depot = Object::Depot->new( class => 'CHI', # CHI->new returns a CHI::Driver object. type => InstanceOf[ 'CHI::Driver' ], ); $depot->add_key( sessions => { driver => 'Memory', global => 1, }, ); $depot->store( ip2geo => CHI->new(...) ); my $sessions = $depot->fetch('sessions'); my $ip2geo = $depot->fetch('ip2geo'); =head1 DESCRIPTION Object depots encapsulate object construction so that users of objects do not need to know how to create the objects in order to use them. The primary use case for this library is for storing the connection logic to external services and making these connections globally available to all application logic. See L<Object::Depot::Singleton> for turning your depot object into a global singleton. =cut use Guard qw( guard ); use Object::Depot::Singleton qw(); use Carp qw(); use Role::Tiny qw(); use Scalar::Util qw( blessed ); use Sub::Name qw( subname ); use Types::Common::String qw( NonEmptySimpleStr ); use Types::Standard qw( Bool CodeRef HashRef Object InstanceOf ); sub croak { local $Carp::Internal{'Object::Depot'} = 1; goto &Carp::croak; } sub croakf { my $msg = shift; $msg = sprintf( $msg, @_ ); @_ = ( $msg ); goto &croak; } use Moo; use namespace::clean; sub _normalize_args { my ($self, $args) = @_; return {} if !@$args; return $args->[0] if @$args==1 and ref($args->[0]) eq 'HASH'; return { @$args } unless @$args % 2; croakf( 'Odd number of arguments passed to %s()', scalar( caller ), ); } sub _process_key_arg { my ($self, $args) = @_; my $caller_sub_name = (caller 1)[3]; $caller_sub_name = '__ANON__' if !defined $caller_sub_name; $caller_sub_name =~ s{^.*::}{}; my $key; $key = shift @$args if @$args and !blessed $args->[0]; if ($self->_has_default_key() and !defined $key) { $key = $self->default_key(); } else { croak "No key was passed to $caller_sub_name()" if !defined $key; if (!NonEmptySimpleStr->check( $key )) { $key = defined($key) ? ["$key"] : 'UNDEF'; croak "Invalid key, $key, passed to $caller_sub_name(): " . NonEmptySimpleStr->message( $key ); } } $key = $self->_aliases->{$key} if exists $self->_aliases->{$key}; if ($self->strict_keys() and !exists $self->_key_args->{$key}) { $key = defined($key) ? qq["$key"] : 'UNDEF'; croak "Undeclared key, $key, passed to $caller_sub_name()" } return $key; } sub _export { my $self = shift; my $package = shift; return if !$self->_has_export_name(); my $name = $self->export_name(); my $do_it = $self->always_export(); foreach my $arg (@_) { if (defined($arg) and $arg eq $name) { $do_it = 1; next; } croakf( 'Unknown export, %s, passed to %s', defined($arg) ? qq["$arg"] : 'undef', $package, ); } return if !$do_it; my $sub = subname $name => sub{ $self->fetch(@_) }; { no strict 'refs'; *{"$package\::$name"} = $sub }; return; } has _all_objects => ( is => 'ro', default => sub{ {} }, ); sub _objects { my ($self) = @_; return $self->_all_objects() if !$self->per_process(); my $key = $$; $key .= '-' . threads->tid() if $INC{'threads.pm'}; return $self->_all_objects->{$key} ||= {}; } has _key_args => ( is => 'ro', default => sub{ {} }, ); has _aliases => ( is => 'ro', default => sub{ {} }, ); has _injections => ( is => 'ro', default => sub{ {} }, ); =head1 ARGUMENTS =head2 class class => 'CHI', The class which objects in this depot are expected to be. This argument defaults the L</constructor> and L</type> arguments. Does not have a default. Leaving this argument unset causes L</fetch> to fail on keys that were not first populated with L</store> as the L</constructor> subroutine will just return C<undef>. =cut has class => ( is => 'ro', isa => NonEmptySimpleStr, predicate => '_has_class', ); =head2 constructor constuctor => sub{ my ($args) = @_; return __PACKAGE__->depot->class->new( $args ); }, Set this to a code ref to control how objects get constructed. When declaring a custom constructor be careful not to create memory leaks via circular references. L</create> validates the objects produced by this constructor and will throw an exception if they do not match L</type>. The default code ref is similar to the above example if L</class> is set. If it is not set then the default code ref will return C<undef>. =cut has constructor => ( is => 'lazy', isa => CodeRef, ); my $undef_constructor = sub{ undef }; sub _build_constructor { my ($self) = @_; return $undef_constructor if !$self->_has_class(); return _build_class_constructor( $self->class() ); } sub _build_class_constructor { my ($class) = @_; return sub{ $class->new( @_ ) }; } =head2 type type => InstanceOf[ 'CHI::Driver' ], Set this to a L<Type::Tiny> type to control how objects in the depot are validated when they are stored. Defaults to C<InstanceOf> L</class>, if set. If the class is not set then this defaults to C<Object> (both are from L<Types::Standard>). =cut has type => ( is => 'lazy', isa => InstanceOf[ 'Type::Tiny' ], ); sub _build_type { my ($self) = @_; return InstanceOf[ $self->class() ] if $self->_has_class(); return Object; } =head2 per_process per_process => 1, Turn this on to store objects per-process; meaning, if the TID (thread ID) or PID (process ID) change then this depot will act as if no objects have been stored. Generally you will not want to turn this on. On occasion, though, some objects are not thread or forking safe and it is necessary. Defaults off. =cut has per_process => ( is => 'ro', isa => Bool, default => 0, ); =head2 disable_store disable_store => 1, When on this causes L</store> to silently not store, causing all L</fetch> calls for non-injected keys to return a new object. Defaults off. =cut has disable_store => ( is => 'ro', isa => Bool, default => 0, ); =head2 strict_keys strict_keys => 1, Turn this on to require that all keys used must first be declared via L</add_key> before they can be stored in the depot. Defaults to off, meaning keys may be used without having to pre-declare them. =cut has strict_keys => ( is => 'ro', isa => Bool, default => 0, ); =head2 default_key default_key => 'generic', If no key is passed to key-accepting methods like L</fetch> then they will use this default key if available. Defaults to no default key. =cut has default_key => ( is => 'ro', isa => NonEmptySimpleStr, predicate => '_has_default_key', ); =head2 key_argument key_argument => 'connection_key', When set, this causes L</arguments> to include an extra argument to be passed to the class during object construction. The argument's key will be whatever you set this to and the value will be the key used to fetch the object. You will still need to write the code in your class to capture the argument, such as: has connection_key => ( is=>'ro' ); Defaults to no key argument. =cut has key_argument => ( is => 'ro', isa => NonEmptySimpleStr, predicate => '_has_key_argument', ); =head2 default_arguments default_arguments => { arg => 'value', ... }, When set, these arguments will be included in calls to L</arguments>. Defaults to an empty hash ref. =cut has default_arguments => ( is => 'lazy', isa => HashRef, default => sub{ {} }, ); =head2 export_name export_name => 'myapp_cache', Set the name of a function that L<Object::Depot::Singleton> will export to importers of your depot package. Has no default. If this is not set, then nothing will be exported. =cut has export_name => ( is => 'ro', isa => NonEmptySimpleStr, predicate => '_has_export_name', ); =head2 always_export always_export => 1, Turning this on causes L<Object::Depot::Singleton> to always export the L</export_name>, rather than only when listed in the import arguments. This is synonymous with the difference between L<Exporter>'s C<@EXPORT_OK> and C<@EXPORT>. =cut has always_export => ( is => 'ro', isa => Bool, default => 0, ); =head1 METHODS =head2 fetch my $object = $depot->fetch( $key ); =cut sub fetch { my $self = shift; my $key = $self->_process_key_arg( \@_ ); croak 'Too many arguments passed to fetch()' if @_; return $self->_fetch( $key ); } sub _fetch { my ($self, $key) = @_; my $object = $self->_injections->{ $key }; $object ||= $self->_objects->{$key}; return $object if $object; return undef if !$self->_has_class(); $object = $self->_create( $key, {} ); $self->_store( $key, $object ); return $object; } =head2 store $depot->store( $key => $object ); =cut sub store { my $self = shift; my $key = $self->_process_key_arg( \@_ ); croak 'Too many arguments passed to store()' if @_>1; croak 'Not enough arguments passed to store()' if @_<1; my $object = shift; croakf( 'Invalid object passed to store(): %s', $self->type->get_message( $object ), ) if !$self->type->check( $object ); croak qq[Already stored key, "$key", passed to store()] if exists $self->_objects->{$key}; return $self->_store( $key, $object ); } sub _store { my ($self, $key, $object) = @_; return if $self->disable_store(); $self->_objects->{$key} = $object; return; } =head2 remove $depot->remove( $key ); =cut sub remove { my $self = shift; my $key = $self->_process_key_arg( \@_ ); croak 'Too many arguments passed to remove()' if @_; return $self->_remove( $key ); } sub _remove { my ($self, $key) = @_; return delete $self->_objects->{$key}; } =head2 create my $object = $depot->create( $key, %extra_args ); Gathers arguments from L</arguments> and then calls L</constructor> on them, returning a new object. Extra arguments may be passed and they will take precedence. =cut sub create { my $self = shift; my $key = $self->_process_key_arg( \@_ ); my $extra_args = $self->_normalize_args( \@_ ); return $self->_create( $key, $extra_args ); } sub _create { my ($self, $key, $extra_args) = @_; my $args = $self->_arguments( $key, $extra_args ); my $object = $self->constructor->( $args ); croakf( 'Constructor returned an invalid value, %s, for key %s: %s', defined($object) ? (ref($object) || qq["$object"]) : 'UNDEF', qq["$key"], $self->type->get_message( $object ), ) if !$self->type->check( $object ); return $object; } =head2 arguments my $args = $depot->arguments( $key, %extra_args ); This method returns an arguments hash ref that would be used to instantiate a new L</class> object. You could, for example, use this to produce a base-line set of arguments, then sprinkle in some more, and make yourself a special mock object to be injected. =cut sub arguments { my $self = shift; my $key = $self->_process_key_arg( \@_ ); my $extra_args = $self->_normalize_args( \@_ ); return $self->_arguments( $key, $extra_args ); } sub _arguments { my ($self, $key, $extra_args) = @_; my $args = { %{ $self->default_arguments() }, %{ $self->_key_args->{$key} || {} }, %$extra_args, }; $args->{ $self->key_argument() } = $key if $self->_has_key_argument(); return $args; } =head2 declared_keys my $keys = $depot->declared_keys(); foreach my $key (@$keys) { ... } Returns an array ref containing all the keys declared with L</add_key>. =cut sub declared_keys { my $self = shift; return [ keys %{ $self->_key_args() } ]; } =head2 inject $depot->inject( $key, $object ); Takes an object of your making and forces L</fetch> to return the injected object. This is useful for injecting mock objects in tests. The injected object must validate against L</type>. =cut sub inject { my $self = shift; my $key = $self->_process_key_arg( \@_ ); croak 'Too many arguments passed to inject()' if @_>1; croak 'Not enough arguments passed to inject()' if @_<1; my $object = shift; croakf( 'Invalid object passed to inject(): %s', $self->type->get_message( $object ), ) if !$self->type->check( $object ); croak qq[Already injected key, "$key", passed to inject()] if exists $self->_injections->{$key}; $self->_injections->{$key} = $object; return; } =head2 inject_with_guard my $guard = $depot->inject_with_guard( $key => $object ); This is just like L</inject> except it returns a L<Guard> object which, when it leaves scope and is destroyed, will automatically call L</clear_injection>. =cut sub inject_with_guard { my $self = shift; my $key = $self->_process_key_arg( \@_ ); $self->inject( $key, @_ ); return guard { return $self->clear_injection( $key ); }; } =head2 clear_injection my $object = $depot->clear_injection( $key ); Removes and returns the injected object, restoring the original behavior of L</fetch>. =cut sub clear_injection { my $self = shift; my $key = $self->_process_key_arg( \@_ ); croak 'Too many arguments passed to clear_injection()' if @_; return delete $self->_injections->{$key}; } =head2 injection my $object = $depot->injection( $key ); Returns the injected object, or C<undef> if none has been injected. =cut sub injection { my $self = shift; my $key = $self->_process_key_arg( \@_ ); croak 'Too many arguments passed to injection()' if @_; return $self->_injections->{ $key }; } =head2 has_injection if ($depot->has_injection( $key )) { ... } Returns true if an injection is in place for the specified key. =cut sub has_injection { my $self = shift; my $key = $self->_process_key_arg( \@_ ); croak 'Too many arguments passed to has_injection()' if @_; return exists($self->_injections->{$key}) ? 1 : 0; } =head2 add_key $depot->add_key( $key, %arguments ); Declares a new key and, optionally, the arguments used to construct the L</class> object. Arguments are optional, but if present they will be saved and used by L</fetch> when calling C<new()> (via L</arguments>) on L</class>. =cut sub add_key { my ($self, $key, @args) = @_; croakf( 'Invalid key, %s, passed to add_key(): %s', defined($key) ? qq["$key"] : 'UNDEF', NonEmptySimpleStr->get_message( $key ), ) if !NonEmptySimpleStr->check( $key ); croak "Already declared key, \"$key\", passed to add_key()" if exists $self->_key_args->{$key}; $self->_key_args->{$key} = $self->_normalize_args( \@args ); return; } =head2 alias_key $depot->alias_key( $alias_key => $real_key ); Adds a key that is an alias to another key. =cut sub alias_key { my ($self, $alias, $key) = @_; croakf( 'Invalid alias, %s, passed to alias_key(): %s', defined($alias) ? qq["$alias"] : 'UNDEF', NonEmptySimpleStr->get_message( $alias ), ) if !NonEmptySimpleStr->check( $alias ); croakf( 'Invalid key, %s, passed to alias_key(): %s', defined($key) ? qq["$key"] : 'UNDEF', NonEmptySimpleStr->get_message( $key ), ) if !NonEmptySimpleStr->check( $key ); croak "Already declared alias, \"$alias\", passed to alias_key()" if exists $self->_aliases->{$alias}; croak "Undeclared key, \"$key\", passed to alias_key()" if $self->strict_keys() and !exists $self->_key_args->{$key}; $self->_aliases->{$alias} = $key; return; } 1; __END__ =head1 SUPPORT Please submit bugs and feature requests to the Object-Depot GitHub issue tracker: L<https://github.com/bluefeet/Object-Depot/issues> =head1 ACKNOWLEDGEMENTS Thanks to L<ZipRecruiter|https://www.ziprecruiter.com/> for encouraging their employees to contribute back to the open source ecosystem. Without their dedication to quality software development this distribution would not exist. =head1 AUTHOR Aran Clary Deltac <bluefeet@gmail.com> =head1 COPYRIGHT AND LICENSE Copyright (C) 2020 Aran Clary Deltac This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see L<http://www.gnu.org/licenses/>. =cut