X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FRole%2FTiny.pm;h=9a3ce290a94bb7e9b13c75caefcc74424d2cd53e;hb=667f4e70c519db70d01331d4fe4c33d94740e60a;hp=788309945046e3fd5a5a99e9e9728b3d1fb5c589;hpb=5a2474061ed05c0a95a4cfb299865bc752d7675d;p=gitmo%2FRole-Tiny.git diff --git a/lib/Role/Tiny.pm b/lib/Role/Tiny.pm index 7883099..9a3ce29 100644 --- a/lib/Role/Tiny.pm +++ b/lib/Role/Tiny.pm @@ -1,99 +1,583 @@ package Role::Tiny; -use strictures 1; -use Class::Method::Modifiers (); +sub _getglob { \*{$_[0]} } +sub _getstash { \%{"$_[0]::"} } + +use strict; +use warnings FATAL => 'all'; + +our $VERSION = '1.002004'; # 1.2.4 +$VERSION = eval $VERSION; our %INFO; our %APPLIED_TO; +our %COMPOSED; +our %COMPOSITE_INFO; + +# Module state workaround totally stolen from Zefram's Module::Runtime. + +BEGIN { + *_WORK_AROUND_BROKEN_MODULE_STATE = "$]" < 5.009 ? sub(){1} : sub(){0}; +} + +sub Role::Tiny::__GUARD__::DESTROY { + delete $INC{$_[0]->[0]} if @{$_[0]}; +} -sub _getglob { no strict 'refs'; \*{$_[0]} } +sub _load_module { + (my $proto = $_[0]) =~ s/::/\//g; + $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 = shift; + strict->import; + warnings->import(FATAL => 'all'); + return if $INFO{$target}; # already exported into this package # 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 "${target}::with"} = sub { - die "Only one role supported at a time by with" if @_ > 1; - Role::Tiny->apply_role_to_package($_[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 - } = (); + # is used later) 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} = { $target => undef }; } -sub apply_role_to_package { - my ($class, $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 "Not a Role::Tiny" unless my $info = $INFO{$role}; - my $methods = $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 target symbol table - my $stash = do { no strict 'refs'; \%{"${to}::"}}; - # determine already extant methods of target - my %has_methods; - @has_methods{grep - +((ref($stash->{$_}) eq 'SCALAR') || (*{$stash->{$_}}{CODE})), - keys %$stash + die "${role} is not a Role::Tiny" unless my $info = $INFO{$role}; + + $me->_check_requires($to, $role, @{$info->{requires}||[]}); + + $me->_install_methods($to, $role); + + $me->_install_modifiers($to, $info->{modifiers}); + + # copy our role list into the target's + @{$APPLIED_TO{$to}||={}}{keys %{$APPLIED_TO{$role}}} = (); +} + +sub apply_roles_to_object { + my ($me, $object, @roles) = @_; + die "No roles supplied!" unless @roles; + my $class = ref($object); + bless($object, $me->create_class_with_roles($class, @roles)); + $object; +} + +sub create_class_with_roles { + my ($me, $superclass, @roles) = @_; + + die "No roles supplied!" unless @roles; + + _load_module($superclass); + { + my %seen; + $seen{$_}++ for @roles; + if (my @dupes = grep $seen{$_} > 1, @roles) { + die "Duplicated roles: ".join(', ', @dupes); + } + } + + my $new_name = join( + '__WITH__', $superclass, my $compose_name = join '__AND__', @roles + ); + + return $new_name if $COMPOSED{class}{$new_name}; + + foreach my $role (@roles) { + _load_module($role); + die "${role} is not a Role::Tiny" unless $INFO{$role}; + } + + if ($] >= 5.010) { + require mro; + } else { + require MRO::Compat; + } + + my %conflicts = %{$me->_composite_info_for(@roles)->{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 $INFO{$_}, @roles; + + $me->_check_requires( + $new_name, $compose_name, + do { my %h; @h{map @{$_->{requires}||[]}, @info} = (); keys %h } + ); + + @{$APPLIED_TO{$new_name}||={}}{ + map keys %{$APPLIED_TO{$_}}, @roles } = (); - if (my @requires_fail - = grep !exists $has_methods{$_}, @{$info->{requires}||[]}) { + + $COMPOSED{class}{$new_name} = 1; + 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}}; + delete $conflicts{$_} for $me->_concrete_methods_of($to); + 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; + } + + # 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 + } + + foreach my $role (@roles) { + $me->apply_single_role_to_package($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; + } + delete $methods{$_} for grep keys(%{$methods{$_}}) == 1, keys %methods; + +{ conflicts => \%methods } + }; +} + +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 = $composed_name.'::_BASE'; + # Not using _getglob, since setting @ISA via the typeglob breaks + # inheritance on 5.10.0 if the stash has previously been accessed an + # then a method called on the class (in that order!), which + # ->_install_methods (with the help of ->_install_does) ends up doing. + { no strict 'refs'; @{"${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 } + ) { + push @mod_base, "sub ${modified} { shift->next::method(\@_) }"; + } + 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, $modifiers); + $COMPOSED{role}{$composed_name} = 1; + return $composed_name; +} + +sub _check_requires { + my ($me, $to, $name, @requires) = @_; + if (my @requires_fail = grep !$to->can($_), @requires) { # role -> role, add to requires, role -> class, error out if (my $to_info = $INFO{$to}) { push @{$to_info->{requires}||=[]}, @requires_fail; } else { - die "Can't apply ${role} to ${to} - missing ".join(', ', @requires_fail); + die "Can't apply ${name} to ${to} - missing ".join(', ', @requires_fail); } } +} - my @to_install = grep !exists $has_methods{$_}, keys %$methods; - foreach my $i (@to_install) { +sub _concrete_methods_of { + my ($me, $role) = @_; + my $info = $INFO{$role}; + # 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}; + # rely on the '' key we added in import for "no code here" + 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)}, @{$info->{requires}||[]}); +} + +sub _install_methods { + my ($me, $to, $role) = @_; + + my $info = $INFO{$role}; + + my $methods = $me->_concrete_methods_of($role); + + # grab target symbol table + my $stash = _getstash($to); + + # determine already extant methods of target + my %has_methods; + @has_methods{grep + +(ref($stash->{$_}) || *{$stash->{$_}}{CODE}), + keys %$stash + } = (); + + foreach my $i (grep !exists $has_methods{$_}, keys %$methods) { no warnings 'once'; *{_getglob "${to}::${i}"} = $methods->{$i}; } + + $me->_install_does($to); +} - foreach my $modifier (@{$info->{modifiers}||[]}) { - Class::Method::Modifiers::install_modifier($to, @{$modifier}); +sub _install_modifiers { + my ($me, $to, $modifiers) = @_; + if (my $info = $INFO{$to}) { + push @{$info->{modifiers}}, @{$modifiers||[]}; + } else { + foreach my $modifier (@{$modifiers||[]}) { + $me->_install_single_modifier($to, @$modifier); + } } +} - # 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; - } - +sub _install_single_modifier { + my ($me, @args) = @_; + Class::Method::Modifiers::install_modifier(@args); +} - # copy our role list into the target's - @{$APPLIED_TO{$to}||={}}{keys %{$APPLIED_TO{$role}}} = (); +my $FALLBACK = sub { 0 }; +sub _install_does { + my ($me, $to) = @_; + + # only add does() method to classes + return if $INFO{$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"} = $new_sub; } sub does_role { - my ($package, $role) = @_; - return exists $APPLIED_TO{$package}{$role}; + my ($proto, $role) = @_; + if ($] >= 5.010) { + require mro; + } else { + require MRO::Compat; + } + foreach my $class (@{mro::get_linear_isa(ref($proto)||$proto)}) { + return 1 if exists $APPLIED_TO{$class}{$role}; + } + return 0; } 1; + +=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. + +=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 ($foo->does('Some::Role')) { + ... + } + +will work for classes but to test a role, one must use ::does_role directly. + +Additionally, Role::Tiny will override the standard Perl C method +for your class. However, if C class in your class' inheritance +heirarchy provides C, then Role::Tiny will not override it. + +=head1 METHODS + +=head2 apply_roles_to_package + + Role::Tiny->apply_roles_to_package( + 'Some::Package', 'Some::Role', 'Some::Other::Role' + ); + +Composes role with package. See also L. + +=head2 apply_roles_to_object + + Role::Tiny->apply_roles_to_object($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. + +=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. + +If you don't want method modifiers and do want to be forcibly restricted +to a single role application per class, Ovid's L exists. But +Stevan Little (the L author) and I don't find the additional +restrictions to be amazingly helpful in most cases; L's choices +are more a guide to what you should prefer doing, to our mind, rather than +something that needs to be enforced. + +=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) + +=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