our $VERSION = '0.01';
-my %METAS;
-sub UNIVERSAL::meta {
- my $class = blessed($_[0]) || $_[0];
- $METAS{$class} ||= Class::MOP::Class->initialize($class)
-}
+# my %METAS;
+# sub UNIVERSAL::meta {
+# my $class = blessed($_[0]) || $_[0];
+# $METAS{$class} ||= Class::MOP::Class->initialize($class)
+# }
1;
made for these tools to keep to the spirit of the Perl 5 object
system that we all know and love.
+=head2 What is a Meta Object Protocol?
+
+A meta object protocol is an API to an object system.
+
+To be more specific, it is a set of abstractions of the components of
+an object system (typically things like; classes, object, methods,
+object attributes, etc.). These abstractions can then be used to both
+inspect and manipulate the object system which they describe.
+
+It can be said that there are two MOPs for any object system; the
+implicit MOP, and the explicit MOP. The implicit MOP handles things
+like method dispatch or inheritance, which happen automatically as
+part of how the object system works. The explicit MOP typically
+handles the introspection/reflection features of the object system.
+All object systems have implicit MOPs, without one, they would not
+work. Explict MOPs however as less common, and depending on the
+language can vary from restrictive (Reflection in Java or C#) to
+wide open (CLOS is a perfect example).
+
=head2 Who is this module for?
This module is specifically for anyone who has ever created or
the need to hack the symbol tables, or understand the fine details
of method dispatch.
+=head2 What changes do I have to make to use this module?
+
+This module was designed to be as unintrusive as possible. So many of
+it's features are accessible without B<any> change to your existsing
+code at all. It is meant to be a compliment to your existing code and
+not an intrusion on your code base.
+
+The only feature which requires additions to your code are the
+attribute handling and instance construction features. The only reason
+for this is because Perl 5's object system does not actually have
+these features built in. More information about this feature can be
+found below.
+
+=head2 A Note about Performance?
+
+It is a common misconception that explict MOPs are performance drains.
+But this is not a universal truth at all, it is an side-effect of
+specific implementations. For instance, using Java reflection is much
+slower because the JVM cannot take advantage of any compiler
+optimizations, and the JVM has to deal with much more runtime type
+information as well. Reflection in C# is marginally better as it was
+designed into the language and runtime (the CLR). In contrast, CLOS
+(the Common Lisp Object System) was built to support an explicit MOP,
+and so performance is tuned for it.
+
+This library in particular does it's absolute best to avoid putting
+B<any> drain at all upon your code's performance, while still trying
+to make sure it is fast as well (although only as a secondary
+concern).
+
=head1 PROTOCOLS
The protocol is divided into 3 main sub-protocols:
a specific C<$method_name>. It will I<not> however, attempt to check
if the class inherits the method.
-This will correctly ignore functions imported from other packages,
-and will correctly handle functions defined outside of the package
-that use a fully qualified name (C<sub Package::name { ... }>). It
-will B<not> handle anon functions stored in the package using symbol
-tables, unless the anon function is first named using B<Sub::Name>.
-For instance, this will not return true with C<has_method>:
-
- *{$pkg . '::' . $name} = sub { ... };
+This will correctly handle functions defined outside of the package
+that use a fully qualified name (C<sub Package::name { ... }>).
-However, this will DWIM:
+This will correctly handle functions renamed with B<Sub::Name> and
+installed using the symbol tables. However, if you are naming the
+subroutine outside of the package scope, you must use the fully
+qualified name, including the package name, for C<has_method> to
+correctly identify it.
- my $full_name = $pkg . '::' . $name;
- my $sub = sub { ... };
- Sub::Name::subname($full_name, $sub);
- *{$full_name} = $sub;
+This will attempt to correctly ignore functions imported from other
+packages using B<Exporter>. It breaks down if the function imported
+is an C<__ANON__> sub (such as with C<use constant>), which very well
+may be a valid method being applied to the class.
-B<NOTE:> this code need not be so tedious, it is only this way to
-illustrate my point more clearly.
+In short, this method cannot always be trusted to determine if the
+C<$method_name> is actually a method. However, it will DWIM about
+90% of the time, so it's a small trade off IMO.
=item B<get_method ($method_name)>
# Creation
-sub initialize {
- my ($class, $package_name) = @_;
- (defined $package_name)
- || confess "You must pass a package name";
- bless \$package_name => $class;
+{
+ # Metaclasses are singletons, so we cache them here.
+ # there is no need to worry about destruction though
+ # because they should die only when the program dies.
+ # After all, do package definitions even get reaped?
+ my %METAS;
+ sub initialize {
+ my ($class, $package_name) = @_;
+ (defined $package_name && $package_name)
+ || confess "You must pass a package name";
+ $METAS{$package_name} ||= bless \$package_name => blessed($class) || $class;
+ }
}
sub create {
my ($class, $package_name, $package_version, %options) = @_;
- (defined $package_name)
+ (defined $package_name && $package_name)
|| confess "You must pass a package name";
my $code = "package $package_name;";
$code .= "\$$package_name\:\:VERSION = '$package_version';"
if defined $package_version;
eval $code;
confess "creation of $package_name failed : $@" if $@;
- my $meta = $package_name->meta;
+ my $meta = $class->initialize($package_name);
$meta->superclasses(@{$options{superclasses}})
if exists $options{superclasses};
- # ... rest to come later ...
+ if (exists $options{methods}) {
+ foreach my $method_name (keys %{$options{methods}}) {
+ $meta->add_method($method_name, $options{methods}->{$method_name});
+ }
+ }
return $meta;
}
sub class_precedence_list {
my $self = shift;
+ # NOTE:
+ # We need to check for ciruclar inheirtance here.
+ # This will do nothing if all is well, and blow
+ # up otherwise. Yes, it's an ugly hack, better
+ # suggestions are welcome.
+ { $self->name->isa('This is a test for circular inheritance') }
+ # ... and no back to our regularly scheduled program
(
$self->name,
map {
- $_->meta->class_precedence_list()
+ $self->initialize($_)->class_precedence_list()
} $self->superclasses()
);
}
*{$full_method_name} = subname $full_method_name => $method;
}
-sub has_method {
- my ($self, $method_name, $method) = @_;
- (defined $method_name && $method_name)
- || confess "You must define a method name";
+{
+
+ ## private utility functions for has_method
+ my $_find_subroutine_package_name = sub { eval { svref_2object($_[0])->GV->STASH->NAME } };
+ my $_find_subroutine_name = sub { eval { svref_2object($_[0])->GV->NAME } };
+
+ sub has_method {
+ my ($self, $method_name, $method) = @_;
+ (defined $method_name && $method_name)
+ || confess "You must define a method name";
- my $sub_name = ($self->name . '::' . $method_name);
+ my $sub_name = ($self->name . '::' . $method_name);
- no strict 'refs';
- return 0 unless defined &{$sub_name};
- return 0 unless _find_subroutine_package(\&{$sub_name}) eq $self->name;
- return 1;
+ no strict 'refs';
+ return 0 if !defined(&{$sub_name});
+ return 0 if $_find_subroutine_package_name->(\&{$sub_name}) ne $self->name &&
+ $_find_subroutine_name->(\&{$sub_name}) ne '__ANON__';
+ return 1;
+ }
+
}
sub get_method {
no strict 'refs';
return \&{$self->name . '::' . $method_name}
- if $self->has_method($method_name);
-}
-
-## Private Utility Methods
-
-# initially borrowed from Class::Trait 0.20 - Thanks Ovid :)
-# later re-worked to support subs named with Sub::Name
-sub _find_subroutine_package {
- my $sub = shift;
- my $package = eval { svref_2object($sub)->GV->STASH->NAME };
- confess "Could not determine calling package: $@" if $@;
- return $package;
+ if $self->has_method($method_name);
+ return; # <--- make sure to return undef
}
1;
our @ISA = ('Foo');
}
-my $Foo = Foo->meta();
+my $Foo = Class::MOP::Class->initialize('Foo');
isa_ok($Foo, 'Class::MOP::Class');
-my $Bar = Bar->meta();
+my $Bar = Class::MOP::Class->initialize('Bar');
isa_ok($Bar, 'Class::MOP::Class');
is($Foo->name, 'Foo', '... Foo->name == Foo');
superclasses => [ 'Bar' ]
));
isa_ok($Baz, 'Class::MOP::Class');
-is(Baz->meta, $Baz, '... our metaclasses are singletons');
+is(Class::MOP::Class->initialize('Baz'), $Baz, '... our metaclasses are singletons');
is($Baz->name, 'Baz', '... Baz->name == Baz');
is($Baz->version, '0.10', '... Baz->version == 0.10');
}
is_deeply(
- [ My::D->meta->class_precedence_list ],
+ [ Class::MOP::Class->initialize('My::D')->class_precedence_list ],
[ 'My::D', 'My::B', 'My::A', 'My::C', 'My::A' ],
'... My::D->meta->class_precedence_list == (D B A C A)');
=pod
-+-- B <-+
-| |
-+-> A --+
+ A <-+
+ | |
+ B |
+ | |
+ C --+
=cut
{
package My::2::A;
- our @ISA = ('My::2::B');
+ our @ISA = ('My::2::C');
+
package My::2::B;
- our @ISA = ('My::2::A');
+ our @ISA = ('My::2::A');
+
+ package My::2::C;
+ our @ISA = ('My::2::B');
}
-eval { My::2::B->meta->class_precedence_list };
+eval { Class::MOP::Class->initialize('My::2::B')->class_precedence_list };
ok($@, '... recursive inheritance breaks correctly :)');
=pod
}
is_deeply(
- [ My::3::D->meta->class_precedence_list ],
+ [ Class::MOP::Class->initialize('My::3::D')->class_precedence_list ],
[ 'My::3::D', 'My::3::B', 'My::3::A', 'My::3::C', 'My::3::A', 'My::3::B', 'My::3::A' ],
'... My::3::D->meta->class_precedence_list == (D B A C A B A)');
use_ok('Class::MOP::Class');
}
-{
+{ # This package tries to test &has_method
+ # as exhaustively as possible. More corner
+ # cases are welcome :)
package Foo;
# import a sub
use Scalar::Util 'blessed';
+ use constant FOO_CONSTANT => 'Foo-CONSTANT';
+
# define a sub in package
sub bar { 'Foo::bar' }
*baz = \&bar;
-
+
+ { # method named with Sub::Name inside the package scope
+ no strict 'refs';
+ *{'Foo::floob'} = Sub::Name::subname 'floob' => sub { '!floob!' };
+ }
+
# We hateses the "used only once" warnings
{ my $temp = \&Foo::baz }
{
no strict 'refs';
*{'Foo::bling'} = sub { '$$Bling$$' };
- *{'Foo::bang'} = Sub::Name::subname 'Foo::bang' => sub { '!BANG!' };
+ *{'Foo::bang'} = Sub::Name::subname 'Foo::bang' => sub { '!BANG!' };
+ *{'Foo::boom'} = Sub::Name::subname 'boom' => sub { '!BOOM!' };
+
+ eval "package Foo; sub evaled_foo { 'Foo::evaled_foo' }";
}
}
-my $Foo = Foo->meta;
+my $Foo = Class::MOP::Class->initialize('Foo');
my $foo = sub { 'Foo::foo' };
} '... we added the method successfully';
ok($Foo->has_method('foo'), '... Foo->has_method(foo) (defined with Sub::Name)');
-ok(!$Foo->has_method('blessed'), '... !Foo->has_method(blessed) (imported into Foo)');
+
+is($Foo->get_method('foo'), $foo, '... Foo->get_method(foo) == \&foo');
+is(Foo->foo(), 'Foo::foo', '... Foo->foo() returns "Foo::foo"');
+
+# now check all our other items ...
+
+ok($Foo->has_method('FOO_CONSTANT'), '... Foo->has_method(FOO_CONSTANT) (defined w/ use constant)');
ok($Foo->has_method('bar'), '... Foo->has_method(bar) (defined in Foo)');
ok($Foo->has_method('baz'), '... Foo->has_method(baz) (typeglob aliased within Foo)');
+ok($Foo->has_method('floob'), '... Foo->has_method(floob) (defined in Foo:: using symbol tables and Sub::Name w/out package name)');
ok($Foo->has_method('blah'), '... Foo->has_method(blah) (defined in main:: using fully qualified package name)');
-ok(!$Foo->has_method('bling'), '... !Foo->has_method(bling) (defined in main:: using symbol tables (no Sub::Name))');
+ok($Foo->has_method('bling'), '... Foo->has_method(bling) (defined in main:: using symbol tables (no Sub::Name))');
ok($Foo->has_method('bang'), '... Foo->has_method(bang) (defined in main:: using symbol tables and Sub::Name)');
+ok($Foo->has_method('evaled_foo'), '... Foo->has_method(evaled_foo) (evaled in main::)');
-is($Foo->get_method('foo'), $foo, '... Foo->get_method(foo) == \&foo');
+ok(!$Foo->has_method('blessed'), '... !Foo->has_method(blessed) (imported into Foo)');
+ok(!$Foo->has_method('boom'), '... !Foo->has_method(boom) (defined in main:: using symbol tables and Sub::Name w/out package name)');
-is(Foo->foo(), 'Foo::foo', '... Foo->foo() returns "Foo::foo"');
-is(Foo->bar(), 'Foo::bar', '... Foo->bar() returns "Foo::bar"');
-is(Foo->baz(), 'Foo::bar', '... Foo->baz() returns "Foo::bar" (because it is aliased to &bar)');
+ok(!$Foo->has_method('not_a_real_method'), '... !Foo->has_method(not_a_real_method) (does not exist)');
+is($Foo->get_method('not_a_real_method'), undef, '... Foo->get_method(not_a_real_method) == undef');
+
+# ... test our class creator
+
+my $Bar = Class::MOP::Class->create(
+ 'Bar' => '0.10' => (
+ methods => {
+ foo => sub { 'Bar::foo' },
+ bar => sub { 'Bar::bar' },
+ }
+ ));
+isa_ok($Bar, 'Class::MOP::Class');
+
+ok($Bar->has_method('foo'), '... Bar->has_method(foo)');
+ok($Bar->has_method('bar'), '... Bar->has_method(bar)');
+
+is(Bar->foo, 'Bar::foo', '... Bar->foo == Bar::foo');
+is(Bar->bar, 'Bar::bar', '... Bar->bar == Bar::bar');
+
+lives_ok {
+ $Bar->add_method('foo' => sub { 'Bar::foo v2' });
+} '... overwriting a method is fine';
+
+ok($Bar->has_method('foo'), '... Bar-> (still) has_method(foo)');
+is(Bar->foo, 'Bar::foo v2', '... Bar->foo == "Bar::foo v2"');
projects / gitmo/Class-MOP.git / commitdiff