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PK D�[~���0 �0
Install.pmnu �[��� use strict;
use warnings;
package Sub::Install;
# ABSTRACT: install subroutines into packages easily
$Sub::Install::VERSION = '0.928';
use Carp;
use Scalar::Util ();
#pod =head1 SYNOPSIS
#pod
#pod use Sub::Install;
#pod
#pod Sub::Install::install_sub({
#pod code => sub { ... },
#pod into => $package,
#pod as => $subname
#pod });
#pod
#pod =head1 DESCRIPTION
#pod
#pod This module makes it easy to install subroutines into packages without the
#pod unsightly mess of C<no strict> or typeglobs lying about where just anyone can
#pod see them.
#pod
#pod =func install_sub
#pod
#pod Sub::Install::install_sub({
#pod code => \&subroutine,
#pod into => "Finance::Shady",
#pod as => 'launder',
#pod });
#pod
#pod This routine installs a given code reference into a package as a normal
#pod subroutine. The above is equivalent to:
#pod
#pod no strict 'refs';
#pod *{"Finance::Shady" . '::' . "launder"} = \&subroutine;
#pod
#pod If C<into> is not given, the sub is installed into the calling package.
#pod
#pod If C<code> is not a code reference, it is looked for as an existing sub in the
#pod package named in the C<from> parameter. If C<from> is not given, it will look
#pod in the calling package.
#pod
#pod If C<as> is not given, and if C<code> is a name, C<as> will default to C<code>.
#pod If C<as> is not given, but if C<code> is a code ref, Sub::Install will try to
#pod find the name of the given code ref and use that as C<as>.
#pod
#pod That means that this code:
#pod
#pod Sub::Install::install_sub({
#pod code => 'twitch',
#pod from => 'Person::InPain',
#pod into => 'Person::Teenager',
#pod as => 'dance',
#pod });
#pod
#pod is the same as:
#pod
#pod package Person::Teenager;
#pod
#pod Sub::Install::install_sub({
#pod code => Person::InPain->can('twitch'),
#pod as => 'dance',
#pod });
#pod
#pod =func reinstall_sub
#pod
#pod This routine behaves exactly like C<L</install_sub>>, but does not emit a
#pod warning if warnings are on and the destination is already defined.
#pod
#pod =cut
sub _name_of_code {
my ($code) = @_;
require B;
my $name = B::svref_2object($code)->GV->NAME;
return $name unless $name =~ /\A__ANON__/;
return;
}
# See also Params::Util, to which this code was donated.
sub _CODELIKE {
(Scalar::Util::reftype($_[0])||'') eq 'CODE'
|| Scalar::Util::blessed($_[0])
&& (overload::Method($_[0],'&{}') ? $_[0] : undef);
}
# do the heavy lifting
sub _build_public_installer {
my ($installer) = @_;
sub {
my ($arg) = @_;
my ($calling_pkg) = caller(0);
# I'd rather use ||= but I'm whoring for Devel::Cover.
for (qw(into from)) { $arg->{$_} = $calling_pkg unless $arg->{$_} }
# This is the only absolutely required argument, in many cases.
Carp::croak "named argument 'code' is not optional" unless $arg->{code};
if (_CODELIKE($arg->{code})) {
$arg->{as} ||= _name_of_code($arg->{code});
} else {
Carp::croak
"couldn't find subroutine named $arg->{code} in package $arg->{from}"
unless my $code = $arg->{from}->can($arg->{code});
$arg->{as} = $arg->{code} unless $arg->{as};
$arg->{code} = $code;
}
Carp::croak "couldn't determine name under which to install subroutine"
unless $arg->{as};
$installer->(@$arg{qw(into as code) });
}
}
# do the ugly work
my $_misc_warn_re;
my $_redef_warn_re;
BEGIN {
$_misc_warn_re = qr/
Prototype\ mismatch:\ sub\ .+? |
Constant subroutine .+? redefined
/x;
$_redef_warn_re = qr/Subroutine\ .+?\ redefined/x;
}
my $eow_re;
BEGIN { $eow_re = qr/ at .+? line \d+\.\Z/ };
sub _do_with_warn {
my ($arg) = @_;
my $code = delete $arg->{code};
my $wants_code = sub {
my $code = shift;
sub {
my $warn = $SIG{__WARN__} ? $SIG{__WARN__} : sub { warn @_ }; ## no critic
local $SIG{__WARN__} = sub {
my ($error) = @_;
for (@{ $arg->{suppress} }) {
return if $error =~ $_;
}
for (@{ $arg->{croak} }) {
if (my ($base_error) = $error =~ /\A($_) $eow_re/x) {
Carp::croak $base_error;
}
}
for (@{ $arg->{carp} }) {
if (my ($base_error) = $error =~ /\A($_) $eow_re/x) {
return $warn->(Carp::shortmess $base_error);
}
}
($arg->{default} || $warn)->($error);
};
$code->(@_);
};
};
return $wants_code->($code) if $code;
return $wants_code;
}
sub _installer {
sub {
my ($pkg, $name, $code) = @_;
no strict 'refs'; ## no critic ProhibitNoStrict
*{"$pkg\::$name"} = $code;
return $code;
}
}
BEGIN {
*_ignore_warnings = _do_with_warn({
carp => [ $_misc_warn_re, $_redef_warn_re ]
});
*install_sub = _build_public_installer(_ignore_warnings(_installer));
*_carp_warnings = _do_with_warn({
carp => [ $_misc_warn_re ],
suppress => [ $_redef_warn_re ],
});
*reinstall_sub = _build_public_installer(_carp_warnings(_installer));
*_install_fatal = _do_with_warn({
code => _installer,
croak => [ $_redef_warn_re ],
});
}
#pod =func install_installers
#pod
#pod This routine is provided to allow Sub::Install compatibility with
#pod Sub::Installer. It installs C<install_sub> and C<reinstall_sub> methods into
#pod the package named by its argument.
#pod
#pod Sub::Install::install_installers('Code::Builder'); # just for us, please
#pod Code::Builder->install_sub({ name => $code_ref });
#pod
#pod Sub::Install::install_installers('UNIVERSAL'); # feeling lucky, punk?
#pod Anything::At::All->install_sub({ name => $code_ref });
#pod
#pod The installed installers are similar, but not identical, to those provided by
#pod Sub::Installer. They accept a single hash as an argument. The key/value pairs
#pod are used as the C<as> and C<code> parameters to the C<install_sub> routine
#pod detailed above. The package name on which the method is called is used as the
#pod C<into> parameter.
#pod
#pod Unlike Sub::Installer's C<install_sub> will not eval strings into code, but
#pod will look for named code in the calling package.
#pod
#pod =cut
sub install_installers {
my ($into) = @_;
for my $method (qw(install_sub reinstall_sub)) {
my $code = sub {
my ($package, $subs) = @_;
my ($caller) = caller(0);
my $return;
for (my ($name, $sub) = %$subs) {
$return = Sub::Install->can($method)->({
code => $sub,
from => $caller,
into => $package,
as => $name
});
}
return $return;
};
install_sub({ code => $code, into => $into, as => $method });
}
}
#pod =head1 EXPORTS
#pod
#pod Sub::Install exports C<install_sub> and C<reinstall_sub> only if they are
#pod requested.
#pod
#pod =head2 exporter
#pod
#pod Sub::Install has a never-exported subroutine called C<exporter>, which is used
#pod to implement its C<import> routine. It takes a hashref of named arguments,
#pod only one of which is currently recognize: C<exports>. This must be an arrayref
#pod of subroutines to offer for export.
#pod
#pod This routine is mainly for Sub::Install's own consumption. Instead, consider
#pod L<Sub::Exporter>.
#pod
#pod =cut
sub exporter {
my ($arg) = @_;
my %is_exported = map { $_ => undef } @{ $arg->{exports} };
sub {
my $class = shift;
my $target = caller;
for (@_) {
Carp::croak "'$_' is not exported by $class" if !exists $is_exported{$_};
install_sub({ code => $_, from => $class, into => $target });
}
}
}
BEGIN { *import = exporter({ exports => [ qw(install_sub reinstall_sub) ] }); }
#pod =head1 SEE ALSO
#pod
#pod =over
#pod
#pod =item L<Sub::Installer>
#pod
#pod This module is (obviously) a reaction to Damian Conway's Sub::Installer, which
#pod does the same thing, but does it by getting its greasy fingers all over
#pod UNIVERSAL. I was really happy about the idea of making the installation of
#pod coderefs less ugly, but I couldn't bring myself to replace the ugliness of
#pod typeglobs and loosened strictures with the ugliness of UNIVERSAL methods.
#pod
#pod =item L<Sub::Exporter>
#pod
#pod This is a complete Exporter.pm replacement, built atop Sub::Install.
#pod
#pod =back
#pod
#pod =head1 EXTRA CREDITS
#pod
#pod Several of the tests are adapted from tests that shipped with Damian Conway's
#pod Sub-Installer distribution.
#pod
#pod =cut
1;
__END__
=pod
=encoding UTF-8
=head1 NAME
Sub::Install - install subroutines into packages easily
=head1 VERSION
version 0.928
=head1 SYNOPSIS
use Sub::Install;
Sub::Install::install_sub({
code => sub { ... },
into => $package,
as => $subname
});
=head1 DESCRIPTION
This module makes it easy to install subroutines into packages without the
unsightly mess of C<no strict> or typeglobs lying about where just anyone can
see them.
=head1 FUNCTIONS
=head2 install_sub
Sub::Install::install_sub({
code => \&subroutine,
into => "Finance::Shady",
as => 'launder',
});
This routine installs a given code reference into a package as a normal
subroutine. The above is equivalent to:
no strict 'refs';
*{"Finance::Shady" . '::' . "launder"} = \&subroutine;
If C<into> is not given, the sub is installed into the calling package.
If C<code> is not a code reference, it is looked for as an existing sub in the
package named in the C<from> parameter. If C<from> is not given, it will look
in the calling package.
If C<as> is not given, and if C<code> is a name, C<as> will default to C<code>.
If C<as> is not given, but if C<code> is a code ref, Sub::Install will try to
find the name of the given code ref and use that as C<as>.
That means that this code:
Sub::Install::install_sub({
code => 'twitch',
from => 'Person::InPain',
into => 'Person::Teenager',
as => 'dance',
});
is the same as:
package Person::Teenager;
Sub::Install::install_sub({
code => Person::InPain->can('twitch'),
as => 'dance',
});
=head2 reinstall_sub
This routine behaves exactly like C<L</install_sub>>, but does not emit a
warning if warnings are on and the destination is already defined.
=head2 install_installers
This routine is provided to allow Sub::Install compatibility with
Sub::Installer. It installs C<install_sub> and C<reinstall_sub> methods into
the package named by its argument.
Sub::Install::install_installers('Code::Builder'); # just for us, please
Code::Builder->install_sub({ name => $code_ref });
Sub::Install::install_installers('UNIVERSAL'); # feeling lucky, punk?
Anything::At::All->install_sub({ name => $code_ref });
The installed installers are similar, but not identical, to those provided by
Sub::Installer. They accept a single hash as an argument. The key/value pairs
are used as the C<as> and C<code> parameters to the C<install_sub> routine
detailed above. The package name on which the method is called is used as the
C<into> parameter.
Unlike Sub::Installer's C<install_sub> will not eval strings into code, but
will look for named code in the calling package.
=head1 EXPORTS
Sub::Install exports C<install_sub> and C<reinstall_sub> only if they are
requested.
=head2 exporter
Sub::Install has a never-exported subroutine called C<exporter>, which is used
to implement its C<import> routine. It takes a hashref of named arguments,
only one of which is currently recognize: C<exports>. This must be an arrayref
of subroutines to offer for export.
This routine is mainly for Sub::Install's own consumption. Instead, consider
L<Sub::Exporter>.
=head1 SEE ALSO
=over
=item L<Sub::Installer>
This module is (obviously) a reaction to Damian Conway's Sub::Installer, which
does the same thing, but does it by getting its greasy fingers all over
UNIVERSAL. I was really happy about the idea of making the installation of
coderefs less ugly, but I couldn't bring myself to replace the ugliness of
typeglobs and loosened strictures with the ugliness of UNIVERSAL methods.
=item L<Sub::Exporter>
This is a complete Exporter.pm replacement, built atop Sub::Install.
=back
=head1 EXTRA CREDITS
Several of the tests are adapted from tests that shipped with Damian Conway's
Sub-Installer distribution.
=head1 AUTHOR
Ricardo SIGNES <rjbs@cpan.org>
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2005 by Ricardo SIGNES.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
=cut
PK D�[Bxm{�" �" Exporter/Util.pmnu �[��� use strict;
use warnings;
package Sub::Exporter::Util;
{
$Sub::Exporter::Util::VERSION = '0.987';
}
# ABSTRACT: utilities to make Sub::Exporter easier
use Data::OptList ();
use Params::Util ();
sub curry_method {
my $override_name = shift;
sub {
my ($class, $name) = @_;
$name = $override_name if defined $override_name;
sub { $class->$name(@_); };
}
}
BEGIN { *curry_class = \&curry_method; }
sub curry_chain {
# In the future, we can make \%arg an optional prepend, like the "special"
# args to the default Sub::Exporter-generated import routine.
my (@opt_list) = @_;
my $pairs = Data::OptList::mkopt(\@opt_list, 'args', 'ARRAY');
sub {
my ($class) = @_;
sub {
my $next = $class;
for my $i (0 .. $#$pairs) {
my $pair = $pairs->[ $i ];
unless (Params::Util::_INVOCANT($next)) { ## no critic Private
my $str = defined $next ? "'$next'" : 'undef';
Carp::croak("can't call $pair->[0] on non-invocant $str")
}
my ($method, $args) = @$pair;
if ($i == $#$pairs) {
return $next->$method($args ? @$args : ());
} else {
$next = $next->$method($args ? @$args : ());
}
}
};
}
}
# =head2 name_map
#
# This utility returns an list to be used in specify export generators. For
# example, the following:
#
# exports => {
# name_map(
# '_?_gen' => [ qw(fee fie) ],
# '_make_?' => [ qw(foo bar) ],
# ),
# }
#
# is equivalent to:
#
# exports => {
# name_map(
# fee => \'_fee_gen',
# fie => \'_fie_gen',
# foo => \'_make_foo',
# bar => \'_make_bar',
# ),
# }
#
# This can save a lot of typing, when providing many exports with similarly-named
# generators.
#
# =cut
#
# sub name_map {
# my (%groups) = @_;
#
# my %map;
#
# while (my ($template, $names) = each %groups) {
# for my $name (@$names) {
# (my $export = $template) =~ s/\?/$name/
# or Carp::croak 'no ? found in name_map template';
#
# $map{ $name } = \$export;
# }
# }
#
# return %map;
# }
sub merge_col {
my (%groups) = @_;
my %merged;
while (my ($default_name, $group) = each %groups) {
while (my ($export_name, $gen) = each %$group) {
$merged{$export_name} = sub {
my ($class, $name, $arg, $col) = @_;
my $merged_arg = exists $col->{$default_name}
? { %{ $col->{$default_name} }, %$arg }
: $arg;
if (Params::Util::_CODELIKE($gen)) { ## no critic Private
$gen->($class, $name, $merged_arg, $col);
} else {
$class->$$gen($name, $merged_arg, $col);
}
}
}
}
return %merged;
}
sub __mixin_class_for {
my ($class, $mix_into) = @_;
require Package::Generator;
my $mixin_class = Package::Generator->new_package({
base => "$class\:\:__mixin__",
});
## no critic (ProhibitNoStrict)
no strict 'refs';
if (ref $mix_into) {
unshift @{"$mixin_class" . "::ISA"}, ref $mix_into;
} else {
unshift @{"$mix_into" . "::ISA"}, $mixin_class;
}
return $mixin_class;
}
sub mixin_installer {
sub {
my ($arg, $to_export) = @_;
my $mixin_class = __mixin_class_for($arg->{class}, $arg->{into});
bless $arg->{into} => $mixin_class if ref $arg->{into};
Sub::Exporter::default_installer(
{ %$arg, into => $mixin_class },
$to_export,
);
};
}
sub mixin_exporter {
Carp::cluck "mixin_exporter is deprecated; use mixin_installer instead; it behaves identically";
return mixin_installer;
}
sub like {
sub {
my ($value, $arg) = @_;
Carp::croak "no regex supplied to regex group generator" unless $value;
# Oh, qr//, how you bother me! See the p5p thread from around now about
# fixing this problem... too bad it won't help me. -- rjbs, 2006-04-25
my @values = eval { $value->isa('Regexp') } ? ($value, undef)
: @$value;
while (my ($re, $opt) = splice @values, 0, 2) {
Carp::croak "given pattern for regex group generater is not a Regexp"
unless eval { $re->isa('Regexp') };
my @exports = keys %{ $arg->{config}->{exports} };
my @matching = grep { $_ =~ $re } @exports;
my %merge = $opt ? %$opt : ();
my $prefix = (delete $merge{-prefix}) || '';
my $suffix = (delete $merge{-suffix}) || '';
for my $name (@matching) {
my $as = $prefix . $name . $suffix;
push @{ $arg->{import_args} }, [ $name => { %merge, -as => $as } ];
}
}
1;
}
}
use Sub::Exporter -setup => {
exports => [ qw(
like
name_map
merge_col
curry_method curry_class
curry_chain
mixin_installer mixin_exporter
) ]
};
1;
__END__
=pod
=head1 NAME
Sub::Exporter::Util - utilities to make Sub::Exporter easier
=head1 VERSION
version 0.987
=head1 DESCRIPTION
This module provides a number of utility functions for performing common or
useful operations when setting up a Sub::Exporter configuration. All of the
utilities may be exported, but none are by default.
=head1 THE UTILITIES
=head2 curry_method
exports => {
some_method => curry_method,
}
This utility returns a generator which will produce an invocant-curried version
of a method. In other words, it will export a method call with the exporting
class built in as the invocant.
A module importing the code some the above example might do this:
use Some::Module qw(some_method);
my $x = some_method;
This would be equivalent to:
use Some::Module;
my $x = Some::Module->some_method;
If Some::Module is subclassed and the subclass's import method is called to
import C<some_method>, the subclass will be curried in as the invocant.
If an argument is provided for C<curry_method> it is used as the name of the
curried method to export. This means you could export a Widget constructor
like this:
exports => { widget => curry_method('new') }
This utility may also be called as C<curry_class>, for backwards compatibility.
=head2 curry_chain
C<curry_chain> behaves like C<L</curry_method>>, but is meant for generating
exports that will call several methods in succession.
exports => {
reticulate => curry_chain(
new => gather_data => analyze => [ detail => 100 ] => 'results'
),
}
If imported from Spliner, calling the C<reticulate> routine will be equivalent
to:
Spliner->new->gather_data->analyze(detail => 100)->results;
If any method returns something on which methods may not be called, the routine
croaks.
The arguments to C<curry_chain> form an optlist. The names are methods to be
called and the arguments, if given, are arrayrefs to be dereferenced and passed
as arguments to those methods. C<curry_chain> returns a generator like those
expected by Sub::Exporter.
B<Achtung!> at present, there is no way to pass arguments from the generated
routine to the method calls. This will probably be solved in future revisions
by allowing the opt list's values to be subroutines that will be called with
the generated routine's stack.
=head2 merge_col
exports => {
merge_col(defaults => {
twiddle => \'_twiddle_gen',
tweak => \&_tweak_gen,
}),
}
This utility wraps the given generator in one that will merge the named
collection into its args before calling it. This means that you can support a
"default" collector in multiple exports without writing the code each time.
You can specify as many pairs of collection names and generators as you like.
=head2 mixin_installer
use Sub::Exporter -setup => {
installer => Sub::Exporter::Util::mixin_installer,
exports => [ qw(foo bar baz) ],
};
This utility returns an installer that will install into a superclass and
adjust the ISA importing class to include the newly generated superclass.
If the target of importing is an object, the hierarchy is reversed: the new
class will be ISA the object's class, and the object will be reblessed.
B<Prerequisites>: This utility requires that Package::Generator be installed.
=head2 like
It's a collector that adds imports for anything like given regex.
If you provide this configuration:
exports => [ qw(igrep imap islurp exhausted) ],
collectors => { -like => Sub::Exporter::Util::like },
A user may import from your module like this:
use Your::Iterator -like => qr/^i/; # imports igre, imap, islurp
or
use Your::Iterator -like => [ qr/^i/ => { -prefix => 'your_' } ];
The group-like prefix and suffix arguments are respected; other arguments are
passed on to the generators for matching exports.
=head1 AUTHOR
Ricardo Signes <rjbs@cpan.org>
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2007 by Ricardo Signes.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
=cut
PK D�[��ȶ# �# Exporter/Tutorial.podnu �[���
# PODNAME: Sub::Exporter::Tutorial
# ABSTRACT: a friendly guide to exporting with Sub::Exporter
__END__
=pod
=head1 NAME
Sub::Exporter::Tutorial - a friendly guide to exporting with Sub::Exporter
=head1 VERSION
version 0.987
=head1 DESCRIPTION
=head2 What's an Exporter?
When you C<use> a module, first it is required, then its C<import> method is
called. The Perl documentation tells us that the following two lines are
equivalent:
use Module LIST;
BEGIN { require Module; Module->import(LIST); }
The method named C<import> is the module's I<exporter>, it exports
functions and variables into its caller's namespace.
=head2 The Basics of Sub::Exporter
Sub::Exporter builds a custom exporter which can then be installed into your
module. It builds this method based on configuration passed to its
C<setup_exporter> method.
A very basic use case might look like this:
package Addition;
use Sub::Exporter;
Sub::Exporter::setup_exporter({ exports => [ qw(plus) ]});
sub plus { my ($x, $y) = @_; return $x + $y; }
This would mean that when someone used your Addition module, they could have
its C<plus> routine imported into their package:
use Addition qw(plus);
my $z = plus(2, 2); # this works, because now plus is in the main package
That syntax to set up the exporter, above, is a little verbose, so for the
simple case of just naming some exports, you can write this:
use Sub::Exporter -setup => { exports => [ qw(plus) ] };
...which is the same as the original example -- except that now the exporter is
built and installed at compile time. Well, that and you typed less.
=head2 Using Export Groups
You can specify whole groups of things that should be exportable together.
These are called groups. L<Exporter> calls these tags. To specify groups, you
just pass a C<groups> key in your exporter configuration:
package Food;
use Sub::Exporter -setup => {
exports => [ qw(apple banana beef fluff lox rabbit) ],
groups => {
fauna => [ qw(beef lox rabbit) ],
flora => [ qw(apple banana) ],
}
};
Now, to import all that delicious foreign meat, your consumer needs only to
write:
use Food qw(:fauna);
use Food qw(-fauna);
Either one of the above is acceptable. A colon is more traditional, but
barewords with a leading colon can't be enquoted by a fat arrow. We'll see why
that matters later on.
Groups can contain other groups. If you include a group name (with the leading
dash or colon) in a group definition, it will be expanded recursively when the
exporter is called. The exporter will B<not> recurse into the same group twice
while expanding groups.
There are two special groups: C<all> and C<default>. The C<all> group is
defined for you and contains all exportable subs. You can redefine it,
if you want to export only a subset when all exports are requested. The
C<default> group is the set of routines to export when nothing specific is
requested. By default, there is no C<default> group.
=head2 Renaming Your Imports
Sometimes you want to import something, but you don't like the name as which
it's imported. Sub::Exporter can rename your imports for you. If you wanted
to import C<lox> from the Food package, but you don't like the name, you could
write this:
use Food lox => { -as => 'salmon' };
Now you'd get the C<lox> routine, but it would be called salmon in your
package. You can also rename entire groups by using the C<prefix> option:
use Food -fauna => { -prefix => 'cute_little_' };
Now you can call your C<cute_little_rabbit> routine. (You can also call
C<cute_little_beef>, but that hardly seems as enticing.)
When you define groups, you can include renaming.
use Sub::Exporter -setup => {
exports => [ qw(apple banana beef fluff lox rabbit) ],
groups => {
fauna => [ qw(beef lox), rabbit => { -as => 'coney' } ],
}
};
A prefix on a group like that does the right thing. This is when it's useful
to use a dash instead of a colon to indicate a group: you can put a fat arrow
between the group and its arguments, then.
use Food -fauna => { -prefix => 'lovely_' };
eat( lovely_coney ); # this works
Prefixes also apply recursively. That means that this code works:
use Sub::Exporter -setup => {
exports => [ qw(apple banana beef fluff lox rabbit) ],
groups => {
fauna => [ qw(beef lox), rabbit => { -as => 'coney' } ],
allowed => [ -fauna => { -prefix => 'willing_' }, 'banana' ],
}
};
...
use Food -allowed => { -prefix => 'any_' };
$dinner = any_willing_coney; # yum!
Groups can also be passed a C<-suffix> argument.
Finally, if the C<-as> argument to an exported routine is a reference to a
scalar, a reference to the routine will be placed in that scalar.
=head2 Building Subroutines to Order
Sometimes, you want to export things that you don't have on hand. You might
want to offer customized routines built to the specification of your consumer;
that's just good business! With Sub::Exporter, this is easy.
To offer subroutines to order, you need to provide a generator when you set up
your exporter. A generator is just a routine that returns a new routine.
L<perlref> is talking about these when it discusses closures and function
templates. The canonical example of a generator builds a unique incrementor;
here's how you'd do that with Sub::Exporter;
package Package::Counter;
use Sub::Exporter -setup => {
exports => [ counter => sub { my $i = 0; sub { $i++ } } ],
groups => { default => [ qw(counter) ] },
};
Now anyone can use your Package::Counter module and he'll receive a C<counter>
in his package. It will count up by one, and will never interfere with anyone
else's counter.
This isn't very useful, though, unless the consumer can explain what he wants.
This is done, in part, by supplying arguments when importing. The following
example shows how a generator can take and use arguments:
package Package::Counter;
sub _build_counter {
my ($class, $name, $arg) = @_;
$arg ||= {};
my $i = $arg->{start} || 0;
return sub { $i++ };
}
use Sub::Exporter -setup => {
exports => [ counter => \'_build_counter' ],
groups => { default => [ qw(counter) ] },
};
Now, the consumer can (if he wants) specify a starting value for his counter:
use Package::Counter counter => { start => 10 };
Arguments to a group are passed along to the generators of routines in that
group, but Sub::Exporter arguments -- anything beginning with a dash -- are
never passed in. When groups are nested, the arguments are merged as the
groups are expanded.
Notice, too, that in the example above, we gave a reference to a method I<name>
rather than a method I<implementation>. By giving the name rather than the
subroutine, we make it possible for subclasses of our "Package::Counter" module
to replace the C<_build_counter> method.
When a generator is called, it is passed four parameters:
=over
=item * the invocant on which the exporter was called
=item * the name of the export being generated (not the name it's being installed as)
=item * the arguments supplied for the routine
=item * the collection of generic arguments
=back
The fourth item is the last major feature that hasn't been covered.
=head2 Argument Collectors
Sometimes you will want to accept arguments once that can then be available to
any subroutine that you're going to export. To do this, you specify
collectors, like this:
package Menu::Airline
use Sub::Exporter -setup => {
exports => ... ,
groups => ... ,
collectors => [ qw(allergies ethics) ],
};
Collectors look like normal exports in the import call, but they don't do
anything but collect data which can later be passed to generators. If the
module was used like this:
use Menu::Airline allergies => [ qw(peanuts) ], ethics => [ qw(vegan) ];
...the consumer would get a salad. Also, all the generators would be passed,
as their fourth argument, something like this:
{ allerges => [ qw(peanuts) ], ethics => [ qw(vegan) ] }
Generators may have arguments in their definition, as well. These must be code
refs that perform validation of the collected values. They are passed the
collection value and may return true or false. If they return false, the
exporter will throw an exception.
=head2 Generating Many Routines in One Scope
Sometimes it's useful to have multiple routines generated in one scope. This
way they can share lexical data which is otherwise unavailable. To do this,
you can supply a generator for a group which returns a hashref of names and
code references. This generator is passed all the usual data, and the group
may receive the usual C<-prefix> or C<-suffix> arguments.
=head1 SEE ALSO
=over 4
=item *
L<Sub::Exporter> for complete documentation and references to other exporters
=back
=head1 AUTHOR
Ricardo Signes <rjbs@cpan.org>
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2007 by Ricardo Signes.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
=cut
PK D�[�z֘! �! Exporter/Cookbook.podnu �[���
# ABSTRACT: useful, demonstrative, or stupid Sub::Exporter tricks
# PODNAME: Sub::Exporter::Cookbook
__END__
=pod
=head1 NAME
Sub::Exporter::Cookbook - useful, demonstrative, or stupid Sub::Exporter tricks
=head1 VERSION
version 0.987
=head1 OVERVIEW
Sub::Exporter is a fairly simple tool, and can be used to achieve some very
simple goals. Its basic behaviors and their basic application (that is,
"traditional" exporting of routines) are described in
L<Sub::Exporter::Tutorial> and L<Sub::Exporter>. This document presents
applications that may not be immediately obvious, or that can demonstrate how
certain features can be put to use (for good or evil).
=head1 THE RECIPES
=head2 Exporting Methods as Routines
With Exporter.pm, exporting methods is a non-starter. Sub::Exporter makes it
simple. By using the C<curry_method> utility provided in
L<Sub::Exporter::Util>, a method can be exported with the invocant built in.
package Object::Strenuous;
use Sub::Exporter::Util 'curry_method';
use Sub::Exporter -setup => {
exports => [ objection => curry_method('new') ],
};
With this configuration, the importing code may contain:
my $obj = objection("irrelevant");
...and this will be equivalent to:
my $obj = Object::Strenuous->new("irrelevant");
The built-in invocant is determined by the invocant for the C<import> method.
That means that if we were to subclass Object::Strenuous as follows:
package Object::Strenuous::Repeated;
@ISA = 'Object::Strenuous';
...then importing C<objection> from the subclass would build-in that subclass.
Finally, since the invocant can be an object, you can write something like
this:
package Cypher;
use Sub::Exporter::Util 'curry_method';
use Sub::Exporter -setup => {
exports => [ encypher => curry_method ],
};
with the expectation that C<import> will be called on an instantiated Cypher
object:
BEGIN {
my $cypher = Cypher->new( ... );
$cypher->import('encypher');
}
Now there is a globally-available C<encypher> routine which calls the encypher
method on an otherwise unavailable Cypher object.
=head2 Exporting Methods as Methods
While exporting modules usually export subroutines to be called as subroutines,
it's easy to use Sub::Exporter to export subroutines meant to be called as
methods on the importing package or its objects.
Here's a trivial (and naive) example:
package Mixin::DumpObj;
use Data::Dumper;
use Sub::Exporter -setup => {
exports => [ qw(dump) ]
};
sub dump {
my ($self) = @_;
return Dumper($self);
}
When writing your own object class, you can then import C<dump> to be used as a
method, called like so:
$object->dump;
By assuming that the importing class will provide a certain interface, a
method-exporting module can be used as a simple plugin:
package Number::Plugin::Upto;
use Sub::Exporter -setup => {
into => 'Number',
exports => [ qw(upto) ],
groups => [ default => [ qw(upto) ] ],
};
sub upto {
my ($self) = @_;
return 1 .. abs($self->as_integer);
}
The C<into> line in the configuration says that this plugin will export, by
default, into the Number package, not into the C<use>-ing package. It can be
exported anyway, though, and will work as long as the destination provides an
C<as_integer> method like the one it expects. To import it to a different
destination, one can just write:
use Number::Plugin::Upto { into => 'Quantity' };
=head2 Mixing-in Complex External Behavior
When exporting methods to be used as methods (see above), one very powerful
option is to export methods that are generated routines that maintain an
enclosed reference to the exporting module. This allows a user to import a
single method which is implemented in terms of a complete, well-structured
package.
Here is a very small example:
package Data::Analyzer;
use Sub::Exporter -setup => {
exports => [ analyze => \'_generate_analyzer' ],
};
sub _generate_analyzer {
my ($mixin, $name, $arg, $col) = @_;
return sub {
my ($self) = @_;
my $values = [ $self->values ];
my $analyzer = $mixin->new($values);
$analyzer->perform_analysis;
$analyzer->aggregate_results;
return $analyzer->summary;
};
}
If imported by any package providing a C<values> method, this plugin will
provide a single C<analyze> method that acts as a simple interface to a more
complex set of behaviors.
Even more importantly, because the C<$mixin> value will be the invocant on
which the C<import> was actually called, one can subclass C<Data::Analyzer> and
replace only individual pieces of the complex behavior, making it easy to write
complex, subclassable toolkits with simple single points of entry for external
interfaces.
=head2 Exporting Constants
While Sub::Exporter isn't in the constant-exporting business, it's easy to
export constants by using one of its sister modules, Package::Generator.
package Important::Constants;
use Sub::Exporter -setup => {
collectors => [ constants => \'_set_constants' ],
};
sub _set_constants {
my ($class, $value, $data) = @_;
Package::Generator->assign_symbols(
$data->{into},
[
MEANING_OF_LIFE => \42,
ONE_TRUE_BASE => \13,
FACTORS => [ 6, 9 ],
],
);
return 1;
}
Then, someone can write:
use Important::Constants 'constants';
print "The factors @FACTORS produce $MEANING_OF_LIFE in $ONE_TRUE_BASE.";
(The constants must be exported via a collector, because they are effectively
altering the importing class in a way other than installing subroutines.)
=head2 Altering the Importer's @ISA
It's trivial to make a collector that changes the inheritance of an importing
package:
use Sub::Exporter -setup => {
collectors => { -base => \'_make_base' },
};
sub _make_base {
my ($class, $value, $data) = @_;
my $target = $data->{into};
push @{"$target\::ISA"}, $class;
}
Then, the user of your class can write:
use Some::Class -base;
and become a subclass. This can be quite useful in building, for example, a
module that helps build plugins. We may want a few utilities imported, but we
also want to inherit behavior from some base plugin class;
package Framework::Util;
use Sub::Exporter -setup => {
exports => [ qw(log global_config) ],
groups => [ _plugin => [ qw(log global_config) ]
collectors => { '-plugin' => \'_become_plugin' },
};
sub _become_plugin {
my ($class, $value, $data) = @_;
my $target = $data->{into};
push @{"$target\::ISA"}, $class->plugin_base_class;
push @{ $data->{import_args} }, '-_plugin';
}
Now, you can write a plugin like this:
package Framework::Plugin::AirFreshener;
use Framework::Util -plugin;
=head2 Eating Exporter.pm's Brain
You probably shouldn't actually do this in production. It's offered more as a
demonstration than a suggestion.
sub exporter_upgrade {
my ($pkg) = @_;
my $new_pkg = "$pkg\::UsingSubExporter";
return $new_pkg if $new_pkg->isa($pkg);
Sub::Exporter::setup_exporter({
as => 'import',
into => $new_pkg,
exports => [ @{"$pkg\::EXPORT_OK"} ],
groups => {
%{"$pkg\::EXPORT_TAG"},
default => [ @{"$pkg\::EXPORTS"} ],
},
});
@{"$new_pkg\::ISA"} = $pkg;
return $new_pkg;
}
This routine, given the name of an existing package configured to use
Exporter.pm, returns the name of a new package with a Sub::Exporter-powered
C<import> routine. This lets you import C<Toolkit::exported_sub> into the
current package with the name C<foo> by writing:
BEGIN {
require Toolkit;
exporter_upgrade('Toolkit')->import(exported_sub => { -as => 'foo' })
}
If you're feeling particularly naughty, this routine could have been declared
in the UNIVERSAL package, meaning you could write:
BEGIN {
require Toolkit;
Toolkit->exporter_upgrade->import(exported_sub => { -as => 'foo' })
}
The new package will have all the same exporter configuration as the original,
but will support export and group renaming, including exporting into scalar
references. Further, since Sub::Exporter uses C<can> to find the routine being
exported, the new package may be subclassed and some of its exports replaced.
=head1 AUTHOR
Ricardo Signes <rjbs@cpan.org>
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2007 by Ricardo Signes.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
=cut
PK D�[}���5� 5� Exporter.pmnu �[��� use 5.006;
use strict;
use warnings;
package Sub::Exporter;
{
$Sub::Exporter::VERSION = '0.987';
}
# ABSTRACT: a sophisticated exporter for custom-built routines
use Carp ();
use Data::OptList 0.100 ();
use Params::Util 0.14 (); # _CODELIKE
use Sub::Install 0.92 ();
# Given a potential import name, this returns the group name -- if it's got a
# group prefix.
sub _group_name {
my ($name) = @_;
return if (index q{-:}, (substr $name, 0, 1)) == -1;
return substr $name, 1;
}
# \@groups is a canonicalized opt list of exports and groups this returns
# another canonicalized opt list with groups replaced with relevant exports.
# \%seen is groups we've already expanded and can ignore.
# \%merge is merged options from the group we're descending through.
sub _expand_groups {
my ($class, $config, $groups, $collection, $seen, $merge) = @_;
$seen ||= {};
$merge ||= {};
my @groups = @$groups;
for my $i (reverse 0 .. $#groups) {
if (my $group_name = _group_name($groups[$i][0])) {
my $seen = { %$seen }; # faux-dynamic scoping
splice @groups, $i, 1,
_expand_group($class, $config, $groups[$i], $collection, $seen, $merge);
} else {
# there's nothing to munge in this export's args
next unless my %merge = %$merge;
# we have things to merge in; do so
my $prefix = (delete $merge{-prefix}) || '';
my $suffix = (delete $merge{-suffix}) || '';
if (
Params::Util::_CODELIKE($groups[$i][1]) ## no critic Private
or
Params::Util::_SCALAR0($groups[$i][1]) ## no critic Private
) {
# this entry was build by a group generator
$groups[$i][0] = $prefix . $groups[$i][0] . $suffix;
} else {
my $as
= ref $groups[$i][1]{-as} ? $groups[$i][1]{-as}
: $groups[$i][1]{-as} ? $prefix . $groups[$i][1]{-as} . $suffix
: $prefix . $groups[$i][0] . $suffix;
$groups[$i][1] = { %{ $groups[$i][1] }, %merge, -as => $as };
}
}
}
return \@groups;
}
# \@group is a name/value pair from an opt list.
sub _expand_group {
my ($class, $config, $group, $collection, $seen, $merge) = @_;
$merge ||= {};
my ($group_name, $group_arg) = @$group;
$group_name = _group_name($group_name);
Carp::croak qq(group "$group_name" is not exported by the $class module)
unless exists $config->{groups}{$group_name};
return if $seen->{$group_name}++;
if (ref $group_arg) {
my $prefix = (delete $merge->{-prefix}||'') . ($group_arg->{-prefix}||'');
my $suffix = ($group_arg->{-suffix}||'') . (delete $merge->{-suffix}||'');
$merge = {
%$merge,
%$group_arg,
($prefix ? (-prefix => $prefix) : ()),
($suffix ? (-suffix => $suffix) : ()),
};
}
my $exports = $config->{groups}{$group_name};
if (
Params::Util::_CODELIKE($exports) ## no critic Private
or
Params::Util::_SCALAR0($exports) ## no critic Private
) {
# I'm not very happy with this code for hiding -prefix and -suffix, but
# it's needed, and I'm not sure, offhand, how to make it better.
# -- rjbs, 2006-12-05
my $group_arg = $merge ? { %$merge } : {};
delete $group_arg->{-prefix};
delete $group_arg->{-suffix};
my $group = Params::Util::_CODELIKE($exports) ## no critic Private
? $exports->($class, $group_name, $group_arg, $collection)
: $class->$$exports($group_name, $group_arg, $collection);
Carp::croak qq(group generator "$group_name" did not return a hashref)
if ref $group ne 'HASH';
my $stuff = [ map { [ $_ => $group->{$_} ] } keys %$group ];
return @{
_expand_groups($class, $config, $stuff, $collection, $seen, $merge)
};
} else {
$exports
= Data::OptList::mkopt($exports, "$group_name exports");
return @{
_expand_groups($class, $config, $exports, $collection, $seen, $merge)
};
}
}
sub _mk_collection_builder {
my ($col, $etc) = @_;
my ($config, $import_args, $class, $into) = @$etc;
my %seen;
sub {
my ($collection) = @_;
my ($name, $value) = @$collection;
Carp::croak "collection $name provided multiple times in import"
if $seen{ $name }++;
if (ref(my $hook = $config->{collectors}{$name})) {
my $arg = {
name => $name,
config => $config,
import_args => $import_args,
class => $class,
into => $into,
};
my $error_msg = "collection $name failed validation";
if (Params::Util::_SCALAR0($hook)) { ## no critic Private
Carp::croak $error_msg unless $class->$$hook($value, $arg);
} else {
Carp::croak $error_msg unless $hook->($value, $arg);
}
}
$col->{ $name } = $value;
}
}
# Given a config and pre-canonicalized importer args, remove collections from
# the args and return them.
sub _collect_collections {
my ($config, $import_args, $class, $into) = @_;
my @collections
= map { splice @$import_args, $_, 1 }
grep { exists $config->{collectors}{ $import_args->[$_][0] } }
reverse 0 .. $#$import_args;
unshift @collections, [ INIT => {} ] if $config->{collectors}{INIT};
my $col = {};
my $builder = _mk_collection_builder($col, \@_);
for my $collection (@collections) {
$builder->($collection)
}
return $col;
}
sub setup_exporter {
my ($config) = @_;
Carp::croak 'into and into_level may not both be supplied to exporter'
if exists $config->{into} and exists $config->{into_level};
my $as = delete $config->{as} || 'import';
my $into
= exists $config->{into} ? delete $config->{into}
: exists $config->{into_level} ? caller(delete $config->{into_level})
: caller(0);
my $import = build_exporter($config);
Sub::Install::reinstall_sub({
code => $import,
into => $into,
as => $as,
});
}
sub _key_intersection {
my ($x, $y) = @_;
my %seen = map { $_ => 1 } keys %$x;
my @names = grep { $seen{$_} } keys %$y;
}
# Given the config passed to setup_exporter, which contains sugary opt list
# data, rewrite the opt lists into hashes, catch a few kinds of invalid
# configurations, and set up defaults. Since the config is a reference, it's
# rewritten in place.
my %valid_config_key;
BEGIN {
%valid_config_key =
map { $_ => 1 }
qw(as collectors installer generator exports groups into into_level),
qw(exporter), # deprecated
}
sub _assert_collector_names_ok {
my ($collectors) = @_;
for my $reserved_name (grep { /\A[_A-Z]+\z/ } keys %$collectors) {
Carp::croak "unknown reserved collector name: $reserved_name"
if $reserved_name ne 'INIT';
}
}
sub _rewrite_build_config {
my ($config) = @_;
if (my @keys = grep { not exists $valid_config_key{$_} } keys %$config) {
Carp::croak "unknown options (@keys) passed to Sub::Exporter";
}
Carp::croak q(into and into_level may not both be supplied to exporter)
if exists $config->{into} and exists $config->{into_level};
# XXX: Remove after deprecation period.
if ($config->{exporter}) {
Carp::cluck "'exporter' argument to build_exporter is deprecated. Use 'installer' instead; the semantics are identical.";
$config->{installer} = delete $config->{exporter};
}
Carp::croak q(into and into_level may not both be supplied to exporter)
if exists $config->{into} and exists $config->{into_level};
for (qw(exports collectors)) {
$config->{$_} = Data::OptList::mkopt_hash(
$config->{$_},
$_,
[ 'CODE', 'SCALAR' ],
);
}
_assert_collector_names_ok($config->{collectors});
if (my @names = _key_intersection(@$config{qw(exports collectors)})) {
Carp::croak "names (@names) used in both collections and exports";
}
$config->{groups} = Data::OptList::mkopt_hash(
$config->{groups},
'groups',
[
'HASH', # standard opt list
'ARRAY', # standard opt list
'CODE', # group generator
'SCALAR', # name of group generation method
]
);
# by default, export nothing
$config->{groups}{default} ||= [];
# by default, build an all-inclusive 'all' group
$config->{groups}{all} ||= [ keys %{ $config->{exports} } ];
$config->{generator} ||= \&default_generator;
$config->{installer} ||= \&default_installer;
}
sub build_exporter {
my ($config) = @_;
_rewrite_build_config($config);
my $import = sub {
my ($class) = shift;
# XXX: clean this up -- rjbs, 2006-03-16
my $special = (ref $_[0]) ? shift(@_) : {};
Carp::croak q(into and into_level may not both be supplied to exporter)
if exists $special->{into} and exists $special->{into_level};
if ($special->{exporter}) {
Carp::cluck "'exporter' special import argument is deprecated. Use 'installer' instead; the semantics are identical.";
$special->{installer} = delete $special->{exporter};
}
my $into
= defined $special->{into} ? delete $special->{into}
: defined $special->{into_level} ? caller(delete $special->{into_level})
: defined $config->{into} ? $config->{into}
: defined $config->{into_level} ? caller($config->{into_level})
: caller(0);
my $generator = delete $special->{generator} || $config->{generator};
my $installer = delete $special->{installer} || $config->{installer};
# this builds a AOA, where the inner arrays are [ name => value_ref ]
my $import_args = Data::OptList::mkopt([ @_ ]);
# is this right? defaults first or collectors first? -- rjbs, 2006-06-24
$import_args = [ [ -default => undef ] ] unless @$import_args;
my $collection = _collect_collections($config, $import_args, $class, $into);
my $to_import = _expand_groups($class, $config, $import_args, $collection);
# now, finally $import_arg is really the "to do" list
_do_import(
{
class => $class,
col => $collection,
config => $config,
into => $into,
generator => $generator,
installer => $installer,
},
$to_import,
);
};
return $import;
}
sub _do_import {
my ($arg, $to_import) = @_;
my @todo;
for my $pair (@$to_import) {
my ($name, $import_arg) = @$pair;
my ($generator, $as);
if ($import_arg and Params::Util::_CODELIKE($import_arg)) { ## no critic
# This is the case when a group generator has inserted name/code pairs.
$generator = sub { $import_arg };
$as = $name;
} else {
$import_arg = { $import_arg ? %$import_arg : () };
Carp::croak qq("$name" is not exported by the $arg->{class} module)
unless exists $arg->{config}{exports}{$name};
$generator = $arg->{config}{exports}{$name};
$as = exists $import_arg->{-as} ? (delete $import_arg->{-as}) : $name;
}
my $code = $arg->{generator}->(
{
class => $arg->{class},
name => $name,
arg => $import_arg,
col => $arg->{col},
generator => $generator,
}
);
push @todo, $as, $code;
}
$arg->{installer}->(
{
class => $arg->{class},
into => $arg->{into},
col => $arg->{col},
},
\@todo,
);
}
## Cute idea, possibly for future use: also supply an "unimport" for:
## no Module::Whatever qw(arg arg arg);
# sub _unexport {
# my (undef, undef, undef, undef, undef, $as, $into) = @_;
#
# if (ref $as eq 'SCALAR') {
# undef $$as;
# } elsif (ref $as) {
# Carp::croak "invalid reference type for $as: " . ref $as;
# } else {
# no strict 'refs';
# delete &{$into . '::' . $as};
# }
# }
sub default_generator {
my ($arg) = @_;
my ($class, $name, $generator) = @$arg{qw(class name generator)};
if (not defined $generator) {
my $code = $class->can($name)
or Carp::croak "can't locate exported subroutine $name via $class";
return $code;
}
# I considered making this "$class->$generator(" but it seems that
# overloading precedence would turn an overloaded-as-code generator object
# into a string before code. -- rjbs, 2006-06-11
return $generator->($class, $name, $arg->{arg}, $arg->{col})
if Params::Util::_CODELIKE($generator); ## no critic Private
# This "must" be a scalar reference, to a generator method name.
# -- rjbs, 2006-12-05
return $class->$$generator($name, $arg->{arg}, $arg->{col});
}
sub default_installer {
my ($arg, $to_export) = @_;
for (my $i = 0; $i < @$to_export; $i += 2) {
my ($as, $code) = @$to_export[ $i, $i+1 ];
# Allow as isa ARRAY to push onto an array?
# Allow into isa HASH to install name=>code into hash?
if (ref $as eq 'SCALAR') {
$$as = $code;
} elsif (ref $as) {
Carp::croak "invalid reference type for $as: " . ref $as;
} else {
Sub::Install::reinstall_sub({
code => $code,
into => $arg->{into},
as => $as
});
}
}
}
sub default_exporter {
Carp::cluck "default_exporter is deprecated; call default_installer instead; the semantics are identical";
goto &default_installer;
}
setup_exporter({
exports => [
qw(setup_exporter build_exporter),
_import => sub { build_exporter($_[2]) },
],
groups => {
all => [ qw(setup_exporter build_export) ],
},
collectors => { -setup => \&_setup },
});
sub _setup {
my ($value, $arg) = @_;
if (ref $value eq 'HASH') {
push @{ $arg->{import_args} }, [ _import => { -as => 'import', %$value } ];
return 1;
} elsif (ref $value eq 'ARRAY') {
push @{ $arg->{import_args} },
[ _import => { -as => 'import', exports => $value } ];
return 1;
}
return;
}
"jn8:32"; # <-- magic true value
__END__
=pod
=head1 NAME
Sub::Exporter - a sophisticated exporter for custom-built routines
=head1 VERSION
version 0.987
=head1 SYNOPSIS
Sub::Exporter must be used in two places. First, in an exporting module:
# in the exporting module:
package Text::Tweaker;
use Sub::Exporter -setup => {
exports => [
qw(squish titlecase), # always works the same way
reformat => \&build_reformatter, # generator to build exported function
trim => \&build_trimmer,
indent => \&build_indenter,
],
collectors => [ 'defaults' ],
};
Then, in an importing module:
# in the importing module:
use Text::Tweaker
'squish',
indent => { margin => 5 },
reformat => { width => 79, justify => 'full', -as => 'prettify_text' },
defaults => { eol => 'CRLF' };
With this setup, the importing module ends up with three routines: C<squish>,
C<indent>, and C<prettify_text>. The latter two have been built to the
specifications of the importer -- they are not just copies of the code in the
exporting package.
=head1 DESCRIPTION
B<ACHTUNG!> If you're not familiar with Exporter or exporting, read
L<Sub::Exporter::Tutorial> first!
=head2 Why Generators?
The biggest benefit of Sub::Exporter over existing exporters (including the
ubiquitous Exporter.pm) is its ability to build new coderefs for export, rather
than to simply export code identical to that found in the exporting package.
If your module's consumers get a routine that works like this:
use Data::Analyze qw(analyze);
my $value = analyze($data, $tolerance, $passes);
and they constantly pass only one or two different set of values for the
non-C<$data> arguments, your code can benefit from Sub::Exporter. By writing a
simple generator, you can let them do this, instead:
use Data::Analyze
analyze => { tolerance => 0.10, passes => 10, -as => analyze10 },
analyze => { tolerance => 0.15, passes => 50, -as => analyze50 };
my $value = analyze10($data);
The package with the generator for that would look something like this:
package Data::Analyze;
use Sub::Exporter -setup => {
exports => [
analyze => \&build_analyzer,
],
};
sub build_analyzer {
my ($class, $name, $arg) = @_;
return sub {
my $data = shift;
my $tolerance = shift || $arg->{tolerance};
my $passes = shift || $arg->{passes};
analyze($data, $tolerance, $passes);
}
}
Your module's user now has to do less work to benefit from it -- and remember,
you're often your own user! Investing in customized subroutines is an
investment in future laziness.
This also avoids a common form of ugliness seen in many modules: package-level
configuration. That is, you might have seen something like the above
implemented like so:
use Data::Analyze qw(analyze);
$Data::Analyze::default_tolerance = 0.10;
$Data::Analyze::default_passes = 10;
This might save time, until you have multiple modules using Data::Analyze.
Because there is only one global configuration, they step on each other's toes
and your code begins to have mysterious errors.
Generators can also allow you to export class methods to be called as
subroutines:
package Data::Methodical;
use Sub::Exporter -setup => { exports => { some_method => \&_curry_class } };
sub _curry_class {
my ($class, $name) = @_;
sub { $class->$name(@_); };
}
Because of the way that exporters and Sub::Exporter work, any package that
inherits from Data::Methodical can inherit its exporter and override its
C<some_method>. If a user imports C<some_method> from that package, he'll
receive a subroutine that calls the method on the subclass, rather than on
Data::Methodical itself.
=head2 Other Customizations
Building custom routines with generators isn't the only way that Sub::Exporters
allows the importing code to refine its use of the exported routines. They may
also be renamed to avoid naming collisions.
Consider the following code:
# this program determines to which circle of Hell you will be condemned
use Morality qw(sin virtue); # for calculating viciousness
use Math::Trig qw(:all); # for dealing with circles
The programmer has inadvertently imported two C<sin> routines. The solution,
in Exporter.pm-based modules, would be to import only one and then call the
other by its fully-qualified name. Alternately, the importer could write a
routine that did so, or could mess about with typeglobs.
How much easier to write:
# this program determines to which circle of Hell you will be condemned
use Morality qw(virtue), sin => { -as => 'offense' };
use Math::Trig -all => { -prefix => 'trig_' };
and to have at one's disposal C<offense> and C<trig_sin> -- not to mention
C<trig_cos> and C<trig_tan>.
=head1 EXPORTER CONFIGURATION
You can configure an exporter for your package by using Sub::Exporter like so:
package Tools;
use Sub::Exporter
-setup => { exports => [ qw(function1 function2 function3) ] };
This is the simplest way to use the exporter, and is basically equivalent to
this:
package Tools;
use base qw(Exporter);
our @EXPORT_OK = qw(function1 function2 function3);
Any basic use of Sub::Exporter will look like this:
package Tools;
use Sub::Exporter -setup => \%config;
The following keys are valid in C<%config>:
exports - a list of routines to provide for exporting; each routine may be
followed by generator
groups - a list of groups to provide for exporting; each must be followed by
either (a) a list of exports, possibly with arguments for each
export, or (b) a generator
collectors - a list of names into which values are collected for use in
routine generation; each name may be followed by a validator
In addition to the basic options above, a few more advanced options may be
passed:
into_level - how far up the caller stack to look for a target (default 0)
into - an explicit target (package) into which to export routines
In other words: Sub::Exporter installs a C<import> routine which, when called,
exports routines to the calling namespace. The C<into> and C<into_level>
options change where those exported routines are installed.
generator - a callback used to produce the code that will be installed
default: Sub::Exporter::default_generator
installer - a callback used to install the code produced by the generator
default: Sub::Exporter::default_installer
For information on how these callbacks are used, see the documentation for
C<L</default_generator>> and C<L</default_installer>>.
=head2 Export Configuration
The C<exports> list may be provided as an array reference or a hash reference.
The list is processed in such a way that the following are equivalent:
{ exports => [ qw(foo bar baz), quux => \&quux_generator ] }
{ exports =>
{ foo => undef, bar => undef, baz => undef, quux => \&quux_generator } }
Generators are code that return coderefs. They are called with four
parameters:
$class - the class whose exporter has been called (the exporting class)
$name - the name of the export for which the routine is being build
\%arg - the arguments passed for this export
\%col - the collections for this import
Given the configuration in the L</SYNOPSIS>, the following C<use> statement:
use Text::Tweaker
reformat => { -as => 'make_narrow', width => 33 },
defaults => { eol => 'CR' };
would result in the following call to C<&build_reformatter>:
my $code = build_reformatter(
'Text::Tweaker',
'reformat',
{ width => 33 }, # note that -as is not passed in
{ defaults => { eol => 'CR' } },
);
The returned coderef (C<$code>) would then be installed as C<make_narrow> in the
calling package.
Instead of providing a coderef in the configuration, a reference to a method
name may be provided. This method will then be called on the invocant of the
C<import> method. (In this case, we do not pass the C<$class> parameter, as it
would be redundant.)
=head2 Group Configuration
The C<groups> list can be passed in the same forms as C<exports>. Groups must
have values to be meaningful, which may either list exports that make up the
group (optionally with arguments) or may provide a way to build the group.
The simpler case is the first: a group definition is a list of exports. Here's
the example that could go in exporter in the L</SYNOPSIS>.
groups => {
default => [ qw(reformat) ],
shorteners => [ qw(squish trim) ],
email_safe => [
'indent',
reformat => { -as => 'email_format', width => 72 }
],
},
Groups are imported by specifying their name prefixed be either a dash or a
colon. This line of code would import the C<shorteners> group:
use Text::Tweaker qw(-shorteners);
Arguments passed to a group when importing are merged into the groups options
and passed to any relevant generators. Groups can contain other groups, but
looping group structures are ignored.
The other possible value for a group definition, a coderef, allows one
generator to build several exportable routines simultaneously. This is useful
when many routines must share enclosed lexical variables. The coderef must
return a hash reference. The keys will be used as export names and the values
are the subs that will be exported.
This example shows a simple use of the group generator.
package Data::Crypto;
use Sub::Exporter -setup => { groups => { cipher => \&build_cipher_group } };
sub build_cipher_group {
my ($class, $group, $arg) = @_;
my ($encode, $decode) = build_codec($arg->{secret});
return { cipher => $encode, decipher => $decode };
}
The C<cipher> and C<decipher> routines are built in a group because they are
built together by code which encloses their secret in their environment.
=head3 Default Groups
If a module that uses Sub::Exporter is C<use>d with no arguments, it will try
to export the group named C<default>. If that group has not been specifically
configured, it will be empty, and nothing will happen.
Another group is also created if not defined: C<all>. The C<all> group
contains all the exports from the exports list.
=head2 Collector Configuration
The C<collectors> entry in the exporter configuration gives names which, when
found in the import call, have their values collected and passed to every
generator.
For example, the C<build_analyzer> generator that we saw above could be
rewritten as:
sub build_analyzer {
my ($class, $name, $arg, $col) = @_;
return sub {
my $data = shift;
my $tolerance = shift || $arg->{tolerance} || $col->{defaults}{tolerance};
my $passes = shift || $arg->{passes} || $col->{defaults}{passes};
analyze($data, $tolerance, $passes);
}
}
That would allow the importer to specify global defaults for his imports:
use Data::Analyze
'analyze',
analyze => { tolerance => 0.10, -as => analyze10 },
analyze => { tolerance => 0.15, passes => 50, -as => analyze50 },
defaults => { passes => 10 };
my $A = analyze10($data); # equivalent to analyze($data, 0.10, 10);
my $C = analyze50($data); # equivalent to analyze($data, 0.15, 50);
my $B = analyze($data, 0.20); # equivalent to analyze($data, 0.20, 10);
If values are provided in the C<collectors> list during exporter setup, they
must be code references, and are used to validate the importer's values. The
validator is called when the collection is found, and if it returns false, an
exception is thrown. We could ensure that no one tries to set a global data
default easily:
collectors => { defaults => sub { return (exists $_[0]->{data}) ? 0 : 1 } }
Collector coderefs can also be used as hooks to perform arbitrary actions
before anything is exported.
When the coderef is called, it is passed the value of the collection and a
hashref containing the following entries:
name - the name of the collector
config - the exporter configuration (hashref)
import_args - the arguments passed to the exporter, sans collections (aref)
class - the package on which the importer was called
into - the package into which exports will be exported
Collectors with all-caps names (that is, made up of underscore or capital A
through Z) are reserved for special use. The only currently implemented
special collector is C<INIT>, whose hook (if present in the exporter
configuration) is always run before any other hook.
=head1 CALLING THE EXPORTER
Arguments to the exporter (that is, the arguments after the module name in a
C<use> statement) are parsed as follows:
First, the collectors gather any collections found in the arguments. Any
reference type may be given as the value for a collector. For each collection
given in the arguments, its validator (if any) is called.
Next, groups are expanded. If the group is implemented by a group generator,
the generator is called. There are two special arguments which, if given to a
group, have special meaning:
-prefix - a string to prepend to any export imported from this group
-suffix - a string to append to any export imported from this group
Finally, individual export generators are called and all subs, generated or
otherwise, are installed in the calling package. There is only one special
argument for export generators:
-as - where to install the exported sub
Normally, C<-as> will contain an alternate name for the routine. It may,
however, contain a reference to a scalar. If that is the case, a reference the
generated routine will be placed in the scalar referenced by C<-as>. It will
not be installed into the calling package.
=head2 Special Exporter Arguments
The generated exporter accept some special options, which may be passed as the
first argument, in a hashref.
These options are:
into_level
into
generator
installer
These override the same-named configuration options described in L</EXPORTER
CONFIGURATION>.
=head1 SUBROUTINES
=head2 setup_exporter
This routine builds and installs an C<import> routine. It is called with one
argument, a hashref containing the exporter configuration. Using this, it
builds an exporter and installs it into the calling package with the name
"import." In addition to the normal exporter configuration, a few named
arguments may be passed in the hashref:
into - into what package should the exporter be installed
into_level - into what level up the stack should the exporter be installed
as - what name should the installed exporter be given
By default the exporter is installed with the name C<import> into the immediate
caller of C<setup_exporter>. In other words, if your package calls
C<setup_exporter> without providing any of the three above arguments, it will
have an C<import> routine installed.
Providing both C<into> and C<into_level> will cause an exception to be thrown.
The exporter is built by C<L</build_exporter>>.
=head2 build_exporter
Given a standard exporter configuration, this routine builds and returns an
exporter -- that is, a subroutine that can be installed as a class method to
perform exporting on request.
Usually, this method is called by C<L</setup_exporter>>, which then installs
the exporter as a package's import routine.
=head2 default_generator
This is Sub::Exporter's default generator. It takes bits of configuration that
have been gathered during the import and turns them into a coderef that can be
installed.
my $code = default_generator(\%arg);
Passed arguments are:
class - the class on which the import method was called
name - the name of the export being generated
arg - the arguments to the generator
col - the collections
generator - the generator to be used to build the export (code or scalar ref)
=head2 default_installer
This is Sub::Exporter's default installer. It does what Sub::Exporter
promises: it installs code into the target package.
default_installer(\%arg, \@to_export);
Passed arguments are:
into - the package into which exports should be delivered
C<@to_export> is a list of name/value pairs. The default exporter assigns code
(the values) to named slots (the names) in the given package. If the name is a
scalar reference, the scalar reference is made to point to the code reference
instead.
=head1 EXPORTS
Sub::Exporter also offers its own exports: the C<setup_exporter> and
C<build_exporter> routines described above. It also provides a special "setup"
collector, which will set up an exporter using the parameters passed to it.
Note that the "setup" collector (seen in examples like the L</SYNOPSIS> above)
uses C<build_exporter>, not C<setup_exporter>. This means that the special
arguments like "into" and "as" for C<setup_exporter> are not accepted here.
Instead, you may write something like:
use Sub::Exporter
{ into => 'Target::Package' },
-setup => {
-as => 'do_import',
exports => [ ... ],
}
;
Finding a good reason for wanting to do this is left as an exercise for the
reader.
=head1 COMPARISONS
There are a whole mess of exporters on the CPAN. The features included in
Sub::Exporter set it apart from any existing Exporter. Here's a summary of
some other exporters and how they compare.
=over
=item * L<Exporter> and co.
This is the standard Perl exporter. Its interface is a little clunky, but it's
fast and ubiquitous. It can do some things that Sub::Exporter can't: it can
export things other than routines, it can import "everything in this group
except this symbol," and some other more esoteric things. These features seem
to go nearly entirely unused.
It always exports things exactly as they appear in the exporting module; it
can't rename or customize routines. Its groups ("tags") can't be nested.
L<Exporter::Lite> is a whole lot like Exporter, but it does significantly less:
it supports exporting symbols, but not groups, pattern matching, or negation.
The fact that Sub::Exporter can't export symbols other than subroutines is
a good idea, not a missing feature.
For simple uses, setting up Sub::Exporter is about as easy as Exporter. For
complex uses, Sub::Exporter makes hard things possible, which would not be
possible with Exporter.
When using a module that uses Sub::Exporter, users familiar with Exporter will
probably see no difference in the basics. These two lines do about the same
thing in whether the exporting module uses Exporter or Sub::Exporter.
use Some::Module qw(foo bar baz);
use Some::Module qw(foo :bar baz);
The definition for exporting in Exporter.pm might look like this:
package Some::Module;
use base qw(Exporter);
our @EXPORT_OK = qw(foo bar baz quux);
our %EXPORT_TAGS = (bar => [ qw(bar baz) ]);
Using Sub::Exporter, it would look like this:
package Some::Module;
use Sub::Exporter -setup => {
exports => [ qw(foo bar baz quux) ],
groups => { bar => [ qw(bar baz) ]}
};
Sub::Exporter respects inheritance, so that a package may export inherited
routines, and will export the most inherited version. Exporting methods
without currying away the invocant is a bad idea, but Sub::Exporter allows you
to do just that -- and anyway, there are other uses for this feature, like
packages of exported subroutines which use inheritance specifically to allow
more specialized, but similar, packages.
L<Exporter::Easy> provides a wrapper around the standard Exporter. It makes it
simpler to build groups, but doesn't provide any more functionality. Because
it is a front-end to Exporter, it will store your exporter's configuration in
global package variables.
=item * Attribute-Based Exporters
Some exporters use attributes to mark variables to export. L<Exporter::Simple>
supports exporting any kind of symbol, and supports groups. Using a module
like Exporter or Sub::Exporter, it's easy to look at one place and see what is
exported, but it's impossible to look at a variable definition and see whether
it is exported by that alone. Exporter::Simple makes this trade in reverse:
each variable's declaration includes its export definition, but there is no one
place to look to find a manifest of exports.
More importantly, Exporter::Simple does not add any new features to those of
Exporter. In fact, like Exporter::Easy, it is just a front-end to Exporter, so
it ends up storing its configuration in global package variables. (This means
that there is one place to look for your exporter's manifest, actually. You
can inspect the C<@EXPORT> package variables, and other related package
variables, at runtime.)
L<Perl6::Export> isn't actually attribute based, but looks similar. Its syntax
is borrowed from Perl 6, and implemented by a source filter. It is a prototype
of an interface that is still being designed. It should probably be avoided
for production work. On the other hand, L<Perl6::Export::Attrs> implements
Perl 6-like exporting, but translates it into Perl 5 by providing attributes.
=item * Other Exporters
L<Exporter::Renaming> wraps the standard Exporter to allow it to export symbols
with changed names.
L<Class::Exporter> performs a special kind of routine generation, giving each
importing package an instance of your class, and then exporting the instance's
methods as normal routines. (Sub::Exporter, of course, can easily emulate this
behavior, as shown above.)
L<Exporter::Tidy> implements a form of renaming (using its C<_map> argument)
and of prefixing, and implements groups. It also avoids using package
variables for its configuration.
=back
=head1 TODO
=over
=item * write a set of longer, more demonstrative examples
=item * solidify the "custom exporter" interface (see C<&default_exporter>)
=item * add an "always" group
=back
=head1 THANKS
Hans Dieter Pearcey provided helpful advice while I was writing Sub::Exporter.
Ian Langworth and Shawn Sorichetti asked some good questions and helped me
improve my documentation quite a bit. Yuval Kogman helped me find a bunch of
little problems.
Thanks, guys!
=head1 BUGS
Please report any bugs or feature requests through the web interface at
L<http://rt.cpan.org>. I will be notified, and then you'll automatically be
notified of progress on your bug as I make changes.
=head1 AUTHOR
Ricardo Signes <rjbs@cpan.org>
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2007 by Ricardo Signes.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
=cut
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