X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FRole%2FTiny.pm;h=07fb3d44cbde003db625eb13f2434ae3d8a7b972;hb=cca4fd3e2b7ba5b6b6bd615d4f46ae2aefffd27b;hp=844272f5b23ff58b878d850dfb1345a067bc7292;hpb=1ba114550da04faf77252207e6df621c37d07da7;p=gitmo%2FRole-Tiny.git diff --git a/lib/Role/Tiny.pm b/lib/Role/Tiny.pm index 844272f..07fb3d4 100644 --- a/lib/Role/Tiny.pm +++ b/lib/Role/Tiny.pm @@ -1,72 +1,100 @@ package Role::Tiny; sub _getglob { \*{$_[0]} } +sub _getstash { \%{"$_[0]::"} } use strict; use warnings FATAL => 'all'; +our $VERSION = '1.003002'; +$VERSION = eval $VERSION; + our %INFO; our %APPLIED_TO; our %COMPOSED; +our %COMPOSITE_INFO; +our @ON_ROLE_CREATE; + +# Module state workaround totally stolen from Zefram's Module::Runtime. + +BEGIN { + *_WORK_AROUND_BROKEN_MODULE_STATE = "$]" < 5.009 ? sub(){1} : sub(){0}; + *_MRO_MODULE = "$]" < 5.010 ? sub(){"MRO/Compat.pm"} : sub(){"mro.pm"}; +} + +sub Role::Tiny::__GUARD__::DESTROY { + delete $INC{$_[0]->[0]} if @{$_[0]}; +} sub _load_module { - return 1 if $_[0]->can('can'); (my $proto = $_[0]) =~ s/::/\//g; - require "${proto}.pm"; + $proto .= '.pm'; + return 1 if $INC{$proto}; + # can't just ->can('can') because a sub-package Foo::Bar::Baz + # creates a 'Baz::' key in Foo::Bar's symbol table + return 1 if grep !/::$/, keys %{_getstash($_[0])||{}}; + my $guard = _WORK_AROUND_BROKEN_MODULE_STATE + && bless([ $proto ], 'Role::Tiny::__GUARD__'); + require $proto; + pop @$guard if _WORK_AROUND_BROKEN_MODULE_STATE; return 1; } sub import { my $target = caller; - my $me = $_[0]; - strictures->import; - return if $INFO{$target}; # already exported into this package + my $me = shift; + strict->import; + warnings->import(FATAL => 'all'); + return if $me->is_role($target); # already exported into this package + $INFO{$target}{is_role} = 1; # get symbol table reference - my $stash = do { no strict 'refs'; \%{"${target}::"} }; + my $stash = _getstash($target); # install before/after/around subs foreach my $type (qw(before after around)) { *{_getglob "${target}::${type}"} = sub { require Class::Method::Modifiers; push @{$INFO{$target}{modifiers}||=[]}, [ $type => @_ ]; + return; }; } *{_getglob "${target}::requires"} = sub { push @{$INFO{$target}{requires}||=[]}, @_; + return; }; *{_getglob "${target}::with"} = sub { - die "Only one role supported at a time by with" if @_ > 1; - $me->apply_role_to_package($_[0], $target); + $me->apply_roles_to_package($target, @_); + return; }; - # grab all *non-constant* (ref eq 'SCALAR') subs present + # grab all *non-constant* (stash slot is not a scalarref) subs present # in the symbol table and store their refaddrs (no need to forcibly - # inflate constant subs into real subs) - also add '' to here (this - # is used later) - @{$INFO{$target}{not_methods}={}}{ - '', map { *$_{CODE}||() } grep !(ref eq 'SCALAR'), values %$stash - } = (); + # inflate constant subs into real subs) with a map to the coderefs in + # case of copying or re-use + my @not_methods = (map { *$_{CODE}||() } grep !ref($_), values %$stash); + @{$INFO{$target}{not_methods}={}}{@not_methods} = @not_methods; # a role does itself $APPLIED_TO{$target} = { $target => undef }; + $_->($target) for @ON_ROLE_CREATE; +} + +sub role_application_steps { + qw(_install_methods _check_requires _install_modifiers _copy_applied_list); } -sub apply_role_to_package { - my ($me, $role, $to) = @_; +sub apply_single_role_to_package { + my ($me, $to, $role) = @_; _load_module($role); die "This is apply_role_to_package" if ref($to); - die "${role} is not a Role::Tiny" unless my $info = $INFO{$role}; - - $me->_check_requires($to, $role, @{$info->{requires}||[]}); - - $me->_install_methods($to, $role); + die "${role} is not a Role::Tiny" unless $me->is_role($role); - $me->_install_modifiers($to, $info->{modifiers}); - - # only add does() method to classes and only if they don't have one - if (not $INFO{$to} and not $to->can('does')) { - *{_getglob "${to}::does"} = \&does_role; + foreach my $step ($me->role_application_steps) { + $me->$step($to, $role); } +} +sub _copy_applied_list { + my ($me, $to, $role) = @_; # copy our role list into the target's @{$APPLIED_TO{$to}||={}}{keys %{$APPLIED_TO{$role}}} = (); } @@ -75,8 +103,24 @@ sub apply_roles_to_object { my ($me, $object, @roles) = @_; die "No roles supplied!" unless @roles; my $class = ref($object); - bless($object, $me->create_class_with_roles($class, @roles)); - $object; + # on perl < 5.8.9, magic isn't copied to all ref copies. bless the parameter + # directly, so at least the variable passed to us will get any magic applied + bless($_[1], $me->create_class_with_roles($class, @roles)); +} + +my $role_suffix = 'A000'; +sub _composite_name { + my ($me, $superclass, @roles) = @_; + + my $new_name = join( + '__WITH__', $superclass, my $compose_name = join '__AND__', @roles + ); + + if (length($new_name) > 252) { + $new_name = $COMPOSED{abbrev}{$new_name} + ||= substr($new_name, 0, 250 - length $role_suffix).'__'.$role_suffix++; + } + return wantarray ? ($new_name, $compose_name) : $new_name; } sub create_class_with_roles { @@ -84,32 +128,56 @@ sub create_class_with_roles { die "No roles supplied!" unless @roles; - my $new_name = join('+', $superclass, my $compose_name = join '+', @roles); + _load_module($superclass); + { + my %seen; + $seen{$_}++ for @roles; + if (my @dupes = grep $seen{$_} > 1, @roles) { + die "Duplicated roles: ".join(', ', @dupes); + } + } + + my ($new_name, $compose_name) = $me->_composite_name($superclass, @roles); + return $new_name if $COMPOSED{class}{$new_name}; foreach my $role (@roles) { _load_module($role); - die "${role} is not a Role::Tiny" unless my $info = $INFO{$role}; + die "${role} is not a Role::Tiny" unless $me->is_role($role); } - if ($] > 5.010) { - require mro; - } else { - require MRO::Compat; + require(_MRO_MODULE); + + my $composite_info = $me->_composite_info_for(@roles); + my %conflicts = %{$composite_info->{conflicts}}; + if (keys %conflicts) { + my $fail = + join "\n", + map { + "Method name conflict for '$_' between roles " + ."'".join(' and ', sort values %{$conflicts{$_}})."'" + .", cannot apply these simultaneously to an object." + } keys %conflicts; + die $fail; } my @composable = map $me->_composable_package_for($_), reverse @roles; - *{_getglob("${new_name}::ISA")} = [ @composable, $superclass ]; - - my @info = map +($INFO{$_} ? $INFO{$_} : ()), @roles; + # some methods may not exist in the role, but get generated by + # _composable_package_for (Moose accessors via Moo). filter out anything + # provided by the composable packages, excluding the subs we generated to + # make modifiers work. + my @requires = grep { + my $method = $_; + !grep $_->can($method) && !$COMPOSED{role}{$_}{modifiers_only}{$method}, + @composable + } @{$composite_info->{requires}}; $me->_check_requires( - $new_name, $compose_name, - do { my %h; @h{map @{$_->{requires}||[]}, @info} = (); keys %h } + $superclass, $compose_name, \@requires ); - *{_getglob "${new_name}::does"} = \&does_role unless $new_name->can('does'); + *{_getglob("${new_name}::ISA")} = [ @composable, $superclass ]; @{$APPLIED_TO{$new_name}||={}}{ map keys %{$APPLIED_TO{$_}}, @roles @@ -119,29 +187,128 @@ sub create_class_with_roles { return $new_name; } +# preserved for compat, and apply_roles_to_package calls it to allow an +# updated Role::Tiny to use a non-updated Moo::Role + +sub apply_role_to_package { shift->apply_single_role_to_package(@_) } + +sub apply_roles_to_package { + my ($me, $to, @roles) = @_; + + return $me->apply_role_to_package($to, $roles[0]) if @roles == 1; + + my %conflicts = %{$me->_composite_info_for(@roles)->{conflicts}}; + my @have = grep $to->can($_), keys %conflicts; + delete @conflicts{@have}; + + if (keys %conflicts) { + my $fail = + join "\n", + map { + "Due to a method name conflict between roles " + ."'".join(' and ', sort values %{$conflicts{$_}})."'" + .", the method '$_' must be implemented by '${to}'" + } keys %conflicts; + die $fail; + } + + # conflicting methods are supposed to be treated as required by the + # composed role. we don't have an actual composed role, but because + # we know the target class already provides them, we can instead + # pretend that the roles don't do for the duration of application. + my @role_methods = map $me->_concrete_methods_of($_), @roles; + # separate loops, since local ..., delete ... for ...; creates a scope + local @{$_}{@have} for @role_methods; + delete @{$_}{@have} for @role_methods; + + # the if guard here is essential since otherwise we accidentally create + # a $INFO for something that isn't a Role::Tiny (or Moo::Role) because + # autovivification hates us and wants us to die() + if ($INFO{$to}) { + delete $INFO{$to}{methods}; # reset since we're about to add methods + } + + # backcompat: allow subclasses to use apply_single_role_to_package + # to apply changes. set a local var so ours does nothing. + our %BACKCOMPAT_HACK; + if($me ne __PACKAGE__ + and exists $BACKCOMPAT_HACK{$me} ? $BACKCOMPAT_HACK{$me} : + $BACKCOMPAT_HACK{$me} = + $me->can('role_application_steps') + == \&role_application_steps + && $me->can('apply_single_role_to_package') + != \&apply_single_role_to_package + ) { + foreach my $role (@roles) { + $me->apply_single_role_to_package($to, $role); + } + } + else { + foreach my $step ($me->role_application_steps) { + foreach my $role (@roles) { + $me->$step($to, $role); + } + } + } + $APPLIED_TO{$to}{join('|',@roles)} = 1; +} + +sub _composite_info_for { + my ($me, @roles) = @_; + $COMPOSITE_INFO{join('|', sort @roles)} ||= do { + foreach my $role (@roles) { + _load_module($role); + } + my %methods; + foreach my $role (@roles) { + my $this_methods = $me->_concrete_methods_of($role); + $methods{$_}{$this_methods->{$_}} = $role for keys %$this_methods; + } + my %requires; + @requires{map @{$INFO{$_}{requires}||[]}, @roles} = (); + delete $requires{$_} for keys %methods; + delete $methods{$_} for grep keys(%{$methods{$_}}) == 1, keys %methods; + +{ conflicts => \%methods, requires => [keys %requires] } + }; +} + sub _composable_package_for { my ($me, $role) = @_; my $composed_name = 'Role::Tiny::_COMPOSABLE::'.$role; return $composed_name if $COMPOSED{role}{$composed_name}; $me->_install_methods($composed_name, $role); my $base_name = $composed_name.'::_BASE'; - *{_getglob("${composed_name}::ISA")} = [ $base_name ]; + # force stash to exist so ->can doesn't complain + _getstash($base_name); + # Not using _getglob, since setting @ISA via the typeglob breaks + # inheritance on 5.10.0 if the stash has previously been accessed an + # then a method called on the class (in that order!), which + # ->_install_methods (with the help of ->_install_does) ends up doing. + { no strict 'refs'; @{"${composed_name}::ISA"} = ( $base_name ); } my $modifiers = $INFO{$role}{modifiers}||[]; my @mod_base; - foreach my $modified ( - do { my %h; @h{map $_->[1], @$modifiers} = (); keys %h } - ) { + my @modifiers = grep !$composed_name->can($_), + do { my %h; @h{map @{$_}[1..$#$_-1], @$modifiers} = (); keys %h }; + foreach my $modified (@modifiers) { push @mod_base, "sub ${modified} { shift->next::method(\@_) }"; } - eval(my $code = join "\n", "package ${base_name};", @mod_base); - die "Evaling failed: $@\nTrying to eval:\n${code}" if $@; - $me->_install_modifiers($composed_name, $modifiers); - $COMPOSED{role}{$composed_name} = 1; + my $e; + { + local $@; + eval(my $code = join "\n", "package ${base_name};", @mod_base); + $e = "Evaling failed: $@\nTrying to eval:\n${code}" if $@; + } + die $e if $e; + $me->_install_modifiers($composed_name, $role); + $COMPOSED{role}{$composed_name} = { + modifiers_only => { map { $_ => 1 } @modifiers }, + }; return $composed_name; } sub _check_requires { - my ($me, $to, $name, @requires) = @_; + my ($me, $to, $name, $requires) = @_; + return unless my @requires = @{$requires||$INFO{$name}{requires}||[]}; if (my @requires_fail = grep !$to->can($_), @requires) { # role -> role, add to requires, role -> class, error out if (my $to_info = $INFO{$to}) { @@ -155,25 +322,24 @@ sub _check_requires { sub _concrete_methods_of { my ($me, $role) = @_; my $info = $INFO{$role}; - $info->{methods} ||= do { - # grab role symbol table - my $stash = do { no strict 'refs'; \%{"${role}::"}}; - my $not_methods = $info->{not_methods}; - +{ - # grab all code entries that aren't in the not_methods list - map { - my $code = *{$stash->{$_}}{CODE}; - # rely on the '' key we added in import for "no code here" - exists $not_methods->{$code||''} ? () : ($_ => $code) - } grep !(ref($stash->{$_}) eq 'SCALAR'), keys %$stash - }; + # grab role symbol table + my $stash = _getstash($role); + # reverse so our keys become the values (captured coderefs) in case + # they got copied or re-used since + my $not_methods = { reverse %{$info->{not_methods}||{}} }; + $info->{methods} ||= +{ + # grab all code entries that aren't in the not_methods list + map { + my $code = *{$stash->{$_}}{CODE}; + ( ! $code or exists $not_methods->{$code} ) ? () : ($_ => $code) + } grep !ref($stash->{$_}), keys %$stash }; } sub methods_provided_by { my ($me, $role) = @_; - die "${role} is not a Role::Tiny" unless my $info = $INFO{$role}; - (keys %{$me->_concrete_methods_of($role)}, @{$info->{requires}||[]}); + die "${role} is not a Role::Tiny" unless $me->is_role($role); + (keys %{$me->_concrete_methods_of($role)}, @{$INFO{$role}->{requires}||[]}); } sub _install_methods { @@ -184,23 +350,40 @@ sub _install_methods { my $methods = $me->_concrete_methods_of($role); # grab target symbol table - my $stash = do { no strict 'refs'; \%{"${to}::"}}; + my $stash = _getstash($to); # determine already extant methods of target my %has_methods; @has_methods{grep - +((ref($stash->{$_}) eq 'SCALAR') || (*{$stash->{$_}}{CODE})), + +(ref($stash->{$_}) || *{$stash->{$_}}{CODE}), keys %$stash } = (); foreach my $i (grep !exists $has_methods{$_}, keys %$methods) { no warnings 'once'; - *{_getglob "${to}::${i}"} = $methods->{$i}; + my $glob = _getglob "${to}::${i}"; + *$glob = $methods->{$i}; + + # overloads using method names have the method stored in the scalar slot + # and &overload::nil in the code slot. + next + unless $i =~ /^\(/ + && defined &overload::nil + && $methods->{$i} == \&overload::nil; + + my $overload = ${ *{_getglob "${role}::${i}"}{SCALAR} }; + next + unless defined $overload; + + *$glob = \$overload; } + + $me->_install_does($to); } sub _install_modifiers { - my ($me, $to, $modifiers) = @_; + my ($me, $to, $name) = @_; + return unless my $modifiers = $INFO{$name}{modifiers}; if (my $info = $INFO{$to}) { push @{$info->{modifiers}}, @{$modifiers||[]}; } else { @@ -210,14 +393,306 @@ sub _install_modifiers { } } +my $vcheck_error; + sub _install_single_modifier { my ($me, @args) = @_; + defined($vcheck_error) or $vcheck_error = do { + local $@; + eval { Class::Method::Modifiers->VERSION(1.05); 1 } + ? 0 + : $@ + }; + $vcheck_error and die $vcheck_error; Class::Method::Modifiers::install_modifier(@args); } +my $FALLBACK = sub { 0 }; +sub _install_does { + my ($me, $to) = @_; + + # only add does() method to classes + return if $me->is_role($to); + + # add does() only if they don't have one + *{_getglob "${to}::does"} = \&does_role unless $to->can('does'); + + return + if $to->can('DOES') and $to->can('DOES') != (UNIVERSAL->can('DOES') || 0); + + my $existing = $to->can('DOES') || $to->can('isa') || $FALLBACK; + my $new_sub = sub { + my ($proto, $role) = @_; + Role::Tiny::does_role($proto, $role) or $proto->$existing($role); + }; + no warnings 'redefine'; + *{_getglob "${to}::DOES"} = $new_sub; +} + sub does_role { my ($proto, $role) = @_; - return exists $APPLIED_TO{ref($proto)||$proto}{$role}; + require(_MRO_MODULE); + foreach my $class (@{mro::get_linear_isa(ref($proto)||$proto)}) { + return 1 if exists $APPLIED_TO{$class}{$role}; + } + return 0; +} + +sub is_role { + my ($me, $role) = @_; + return !!($INFO{$role} && $INFO{$role}{is_role}); } 1; +__END__ + +=encoding utf-8 + +=head1 NAME + +Role::Tiny - Roles. Like a nouvelle cuisine portion size slice of Moose. + +=head1 SYNOPSIS + + package Some::Role; + + use Role::Tiny; + + sub foo { ... } + + sub bar { ... } + + around baz => sub { ... } + + 1; + +else where + + package Some::Class; + + use Role::Tiny::With; + + # bar gets imported, but not foo + with 'Some::Role'; + + sub foo { ... } + + # baz is wrapped in the around modifier by Class::Method::Modifiers + sub baz { ... } + + 1; + +If you wanted attributes as well, look at L. + +=head1 DESCRIPTION + +C is a minimalist role composition tool. + +=head1 ROLE COMPOSITION + +Role composition can be thought of as much more clever and meaningful multiple +inheritance. The basics of this implementation of roles is: + +=over 2 + +=item * + +If a method is already defined on a class, that method will not be composed in +from the role. + +=item * + +If a method that the role L to be implemented is not implemented, +role application will fail loudly. + +=back + +Unlike L, where the B class inherited from "wins," role +composition is the other way around, where the class wins. If multiple roles +are applied in a single call (single with statement), then if any of their +provided methods clash, an exception is raised unless the class provides +a method since this conflict indicates a potential problem. + +=head1 IMPORTED SUBROUTINES + +=head2 requires + + requires qw(foo bar); + +Declares a list of methods that must be defined to compose role. + +=head2 with + + with 'Some::Role1'; + + with 'Some::Role1', 'Some::Role2'; + +Composes another role into the current role (or class via L). + +If you have conflicts and want to resolve them in favour of Some::Role1 you +can instead write: + + with 'Some::Role1'; + with 'Some::Role2'; + +If you have conflicts and want to resolve different conflicts in favour of +different roles, please refactor your codebase. + +=head2 before + + before foo => sub { ... }; + +See L<< Class::Method::Modifiers/before method(s) => sub { ... } >> for full +documentation. + +Note that since you are not required to use method modifiers, +L is lazily loaded and we do not declare it as +a dependency. If your L role uses modifiers you must depend on +both L and L. + +=head2 around + + around foo => sub { ... }; + +See L<< Class::Method::Modifiers/around method(s) => sub { ... } >> for full +documentation. + +Note that since you are not required to use method modifiers, +L is lazily loaded and we do not declare it as +a dependency. If your L role uses modifiers you must depend on +both L and L. + +=head2 after + + after foo => sub { ... }; + +See L<< Class::Method::Modifiers/after method(s) => sub { ... } >> for full +documentation. + +Note that since you are not required to use method modifiers, +L is lazily loaded and we do not declare it as +a dependency. If your L role uses modifiers you must depend on +both L and L. + +=head2 Strict and Warnings + +In addition to importing subroutines, using C applies L and +L to the caller. It's possible to +disable these if desired: + + use Role::Tiny; + use warnings NONFATAL => 'all'; + +=head1 SUBROUTINES + +=head2 does_role + + if (Role::Tiny::does_role($foo, 'Some::Role')) { + ... + } + +Returns true if class has been composed with role. + +This subroutine is also installed as ->does on any class a Role::Tiny is +composed into unless that class already has an ->does method, so + + if ($foo->does('Some::Role')) { + ... + } + +will work for classes but to test a role, one must use ::does_role directly. + +Additionally, Role::Tiny will override the standard Perl C method +for your class. However, if C class in your class' inheritance +hierarchy provides C, then Role::Tiny will not override it. + +=head1 METHODS + +=head2 apply_roles_to_package + + Role::Tiny->apply_roles_to_package( + 'Some::Package', 'Some::Role', 'Some::Other::Role' + ); + +Composes role with package. See also L. + +=head2 apply_roles_to_object + + Role::Tiny->apply_roles_to_object($foo, qw(Some::Role1 Some::Role2)); + +Composes roles in order into object directly. Object is reblessed into the +resulting class. + +=head2 create_class_with_roles + + Role::Tiny->create_class_with_roles('Some::Base', qw(Some::Role1 Some::Role2)); + +Creates a new class based on base, with the roles composed into it in order. +New class is returned. + +=head2 is_role + + Role::Tiny->is_role('Some::Role1') + +Returns true if the given package is a role. + +=head1 CAVEATS + +=over 4 + +=item * On perl 5.8.8 and earlier, applying a role to an object won't apply any +overloads from the role to all copies of the object. + +=back + +=head1 SEE ALSO + +L is the attribute-less subset of L; L is +a meta-protocol-less subset of the king of role systems, L. + +Ovid's L provides roles with a similar scope, but without method +modifiers, and having some extra usage restrictions. + +=head1 AUTHOR + +mst - Matt S. Trout (cpan:MSTROUT) + +=head1 CONTRIBUTORS + +dg - David Leadbeater (cpan:DGL) + +frew - Arthur Axel "fREW" Schmidt (cpan:FREW) + +hobbs - Andrew Rodland (cpan:ARODLAND) + +jnap - John Napiorkowski (cpan:JJNAPIORK) + +ribasushi - Peter Rabbitson (cpan:RIBASUSHI) + +chip - Chip Salzenberg (cpan:CHIPS) + +ajgb - Alex J. G. Burzyński (cpan:AJGB) + +doy - Jesse Luehrs (cpan:DOY) + +perigrin - Chris Prather (cpan:PERIGRIN) + +Mithaldu - Christian Walde (cpan:MITHALDU) + +ilmari - Dagfinn Ilmari Mannsåker (cpan:ILMARI) + +tobyink - Toby Inkster (cpan:TOBYINK) + +haarg - Graham Knop (cpan:HAARG) + +=head1 COPYRIGHT + +Copyright (c) 2010-2012 the Role::Tiny L and L +as listed above. + +=head1 LICENSE + +This library is free software and may be distributed under the same terms +as perl itself. + +=cut