NAME

Sub::Meta - handle subroutine meta information

SYNOPSIS

use Sub::Meta;

sub hello($) :method { }
my $meta = Sub::Meta->new(sub => \&hello);
$meta->subname; # => hello

$meta->sub;        # \&hello
$meta->subname;    # hello
$meta->fullname    # main::hello
$meta->stashname   # main
$meta->file        # path/to/file.pl
$meta->line        # 5
$meta->is_constant # !!0
$meta->prototype   # $
$meta->attribute   # ['method']
$meta->is_method   # undef
$meta->parameters  # undef
$meta->returns     # undef
$meta->display     # 'sub hello'

# setter
$meta->set_subname('world');
$meta->subname; # world
$meta->fullname; # main::world

# apply to sub
$meta->apply_prototype('$@');
$meta->prototype; # $@
Sub::Util::prototype($meta->sub); # $@

And you can hold meta information of parameter type and return type. See also Sub::Meta::Parameters and Sub::Meta::Returns.

$meta->set_parameters(args => ['Str']));
$meta->parameters->args; # [ Sub::Meta::Param->new({ type => 'Str' }) ]

$meta->set_args(['Str']);
$meta->args; # [ Sub::Meta::Param->new({ type => 'Str' }) ]

$meta->set_returns('Str');
$meta->returns->scalar; # 'Str'
$meta->returns->list;   # 'Str'

And you can compare meta informations:

my $other = Sub::Meta->new(subname => 'hello');
$meta->is_same_interface($other); # 1
$meta eq $other; # 1

DESCRIPTION

Sub::Meta provides methods to handle subroutine meta information. In addition to information that can be obtained from subroutines using module B etc., subroutines can have meta information such as arguments and return values.

METHODS

new

Constructor of Sub::Meta.

use Sub::Meta;
use Types::Standard -types;

# sub Greeting::hello(Str) -> Str
Sub::Meta->new(
    fullname    => 'Greeting::hello',
    is_constant => 0,
    prototype   => '$',
    attribute   => ['method'],
    is_method   => 1,
    parameters  => { args => [{ type => Str }]},
    returns     => Str,
);

Others are as follows:

# sub add(Int, Int) -> Int
Sub::Meta->new(
    subname => 'add',
    args    => [Int, Int],
    returns => Int,
);

# method hello(Str) -> Str
Sub::Meta->new(
    subname   => 'hello',
    args      => [{ message => Str }],
    is_method => 1,
    returns   => Str,
);

# sub twice(@numbers) -> ArrayRef[Int]
Sub::Meta->new(
    subname   => 'twice',
    args      => [],
    slurpy    => { name => '@numbers' },
    returns   => ArrayRef[Int],
);

# Named parameters:
# sub foo(Str :a) -> Str
Sub::Meta->new(
    subname   => 'foo',
    args      => { a => Str },
    returns   => Str,
);

# is equivalent to
Sub::Meta->new(
    subname   => 'foo',
    args      => [{ name => 'a', isa => Str, named => 1 }],
    returns   => Str,
);

Another way to create a Sub::Meta is to use Sub::Meta::Creator:

use Sub::Meta::Creator;
use Sub::Meta::Finder::FunctionParameters;

my $creator = Sub::Meta::Creator->new(
    finders => [ \&Sub::Meta::Finder::FunctionParameters::find_materials ],
);

use Function::Parameters;
use Types::Standard -types;

method hello(Str $msg) { }
my $meta = $creator->create(\&hello);
# =>
# Sub::Meta
#   args [
#       [0] Sub::Meta::Param->new(name => '$msg', type => Str)
#   ],
#   invocant   Sub::Meta::Param->(name => '$self', invocant => 1),
#   nshift     1,
#   slurpy     !!0

ACCESSORS

sub

Accessor for subroutine.

• sub

  method sub() => Maybe[CodeRef]

  Return a subroutine.

• has_sub

  method has_sub() => Bool

  Whether Sub::Meta has subroutine or not.

• set_sub($sub)

  method set_sub(CodeRef $sub) => $self

  Setter for subroutine.

  sub hello { ... }
  $meta->set_sub(\&hello);
  $meta->sub # => \&hello
  
  # And set subname, stashname
  $meta->subname; # hello
  $meta->stashname; # main

subname

Accessor for subroutine name

• subname

  method subname() => Str

• has_subname

  method has_subname() => Bool

  Whether Sub::Meta has subroutine name or not.

• set_subname($subname)

  method set_subname(Str $subname) => $self

  Setter for subroutine name.

  $meta->subname; # hello
  $meta->set_subname('world');
  $meta->subname; # world
  Sub::Util::subname($meta->sub); # hello (NOT apply to sub)

• apply_subname($subname)

  method apply_subname(Str $subname) => $self

  Sets subroutine name and apply to the subroutine reference.

  $meta->subname; # hello
  $meta->apply_subname('world');
  $meta->subname; # world
  Sub::Util::subname($meta->sub); # world

fullname

Accessor for subroutine full name

• fullname

  method fullname() => Str

  A subroutine full name, e.g. main::hello

• has_fullname

  method has_fullname() => Bool

  Whether Sub::Meta has subroutine full name or not.

• set_fullname($fullname)

  method set_fullname(Str $fullname) => $self

  Setter for subroutine full name.

stashname

Accessor for subroutine stash name

• stashname

  method stashname() => Str

  A subroutine stash name, e.g. main

• has_stashname

  method has_stashname() => Bool

  Whether Sub::Meta has subroutine stash name or not.

• set_stashname($stashname)

  method set_stashname(Str $stashname) => $self

  Setter for subroutine stash name.

subinfo

Accessor for subroutine information

• subinfo

  method subinfo() => Tuple[Str,Str]

  A subroutine information, e.g. ['main', 'hello']

• set_subinfo([$stashname, $subname])

  method set_stashname(Tuple[Str $stashname, Str $subname]) => $self

  Setter for subroutine information.

file, line

Accessor for filename and line where subroutine is defined

• file

  method file() => Maybe[Str]

  A filename where subroutine is defined, e.g. path/to/main.pl.

• has_file

  method has_file() => Bool

  Whether Sub::Meta has a filename where subroutine is defined.

• set_file($filepath)

  method set_file(Str $filepath) => $self

  Setter for file.

• line

  method line() => Maybe[Int]

  A line where the definition of subroutine started, e.g. 5

• has_line

  method has_line() => Bool

  Whether Sub::Meta has a line where the definition of subroutine started.

• set_line($line)

  method set_line(Int $line) => $self

  Setter for line.

is_constant

• is_constant

  method is_constant() => Maybe[Bool]

  If the subroutine is set, it returns whether it is a constant or not, if not set, it returns undef.

• set_is_constant($bool)

  method set_is_constant(Bool $bool) => $self

  Setter for is_constant.

prototype

Accessor for prototype of subroutine reference.

• prototype

  method prototype() => Maybe[Str]

  If the subroutine is set, it returns a prototype of subroutine, if not set, it returns undef. e.g. $@

• has_prototype

  method has_prototype() => Bool

  Whether Sub::Meta has prototype or not.

• set_prototype($prototype)

  method set_prototype(Str $prototype) => $self

  Setter for prototype.

• apply_prototype($prototype)

  method apply_prototype(Str $prototype) => $self

  Sets subroutine prototype and apply to the subroutine reference.

attribute

Accessor for attribute of subroutine reference.

• attribute

  method attribute() => Maybe[ArrayRef[Str]]

  If the subroutine is set, it returns a attribute of subroutine, if not set, it returns undef. e.g. ['method'], undef

• has_attribute

  method has_attribute() => Bool

  Whether Sub::Meta has attribute or not.

• set_attribute($attribute)

  method set_attribute(ArrayRef[Str] $attribute) => $self

  Setter for attribute.

• apply_attribute(@attribute)

  method apply_attribute(Str @attribute) => $self

  Sets subroutine attributes and apply to the subroutine reference.

is_method

• is_method

  method is_method() => Bool

  Whether the subroutine is a method or not.

• set_is_method($bool)

  method set_is_method(Bool $bool) => Bool

  Setter for is_method.

parameters

Accessor for parameters object of Sub::Meta::Parameters

• parameters

  method parameters() => InstanceOf[Sub::Meta::Parameters]

  If the parameters is set, it returns the parameters object.

• set_parameters($parameters)

  method set_parameters(InstanceOf[Sub::Meta::Parameters] $parameters) => $self
  method set_parameters(@sub_meta_parameters_args) => $self

  Sets the parameters object of Sub::Meta::Parameters.

  my $meta = Sub::Meta->new;
  
  my $parameters = Sub::Meta::Parameters->new(args => ['Str']);
  $meta->set_parameters($parameters);
  
  # or
  $meta->set_parameters(args => ['Str']);
  $meta->parameters; # => Sub::Meta::Parameters->new(args => ['Str']);
  
  # alias
  $meta->set_args(['Str']);

• args

  The alias of parameters.args.

• set_args($args)

  The alias of parameters.set_args.

• all_args

  The alias of parameters.all_args.

• nshift

  The alias of parameters.nshift.

• set_nshift($nshift)

  The alias of parameters.set_nshift.

• invocant

  The alias of parameters.invocant.

• invocants

  The alias of parameters.invocants.

• set_invocant($invocant)

  The alias of parameters.set_invocant.

• slurpy

  The alias of parameters.slurpy.

• set_slurpy($slurpy)

  The alias of parameters.set_slurpy.

returns

Accessor for returns object of Sub::Meta::Returns

• returns

  method returns() => InstanceOf[Sub::Meta::Returns]

  If the returns is set, it returns the returns object.

• set_returns($returns)

  method set_returns(InstanceOf[Sub::Meta::Returns] $returns) => $self
  method set_returns(@sub_meta_returns_args) => $self

  Sets the returns object of Sub::Meta::Returns or any object.

  my $meta = Sub::Meta->new;
  $meta->set_returns({ type => 'Type'});
  $meta->returns; # => Sub::Meta::Returns->new({type => 'Type'});
  
  # or
  $meta->set_returns(Sub::Meta::Returns->new(type => 'Foo'));
  $meta->set_returns(MyReturns->new)

METHODS

apply_meta($other_meta)

method apply_meta(InstanceOf[Sub::Meta] $other_meta) => $self

Apply subroutine subname, prototype and attributes of $other_meta.

is_same_interface($other_meta)

method is_same_interface(InstanceOf[Sub::Meta] $other_meta) => Bool

A boolean value indicating whether the subroutine's interface is same or not. Specifically, check whether subname, is_method, parameters and returns are equal.

is_strict_same_interface($other_meta)

Alias for is_same_interface

is_relaxed_same_interface($other_meta)

method is_relaxed_same_interface(InstanceOf[Sub::Meta] $other_meta) => Bool

A boolean value indicating whether the subroutine's interface is relaxed same or not. Specifically, check whether subname, is_method, parameters and returns satisfy the condition of $self side.

Difference between strict and relaxed

If it is is_relaxed_same_interface method, the conditions can be many. For example, the number of arguments can be many. The following code is a test to show the difference between strict and relaxed.

my @tests = (
    {},                { subname => 'foo' },
    {},                { args => [Int] },
    { args => [Int] }, { args => [Int, Str] },
    { args => [Int] }, { args => [Int], slurpy => Str },
    { args => [Int] }, { args => [{ type => Int, name => '$a' }] },
    {},                { returns => Int },
    { returns => { scalar => Int } }, { returns => { scalar => Int, list => Int } },
);

while (@tests) {
    my ($a, $b) = splice @tests, 0, 2;
    my $meta = Sub::Meta->new($a);
    my $other = Sub::Meta->new($b);

    ok !$meta->is_strict_same_interface($other);
    ok $meta->is_relaxed_same_interface($other);
}

is_same_interface_inlined($other_meta_inlined)

method is_same_interface_inlined(InstanceOf[Sub::Meta] $other_meta) => Str

is_strict_same_interface_inlined($other_meta)

Alias for is_same_interface_inlined

Returns inlined is_same_interface string:

use Sub::Meta;
my $meta = Sub::Meta->new(subname => 'hello');
my $inline = $meta->is_same_interface_inlined('$_[0]');
# $inline looks like this:
#    Scalar::Util::blessed($_[0]) && $_[0]->isa('Sub::Meta')
#    && defined $_[0]->subname && 'hello' eq $_[0]->subname
#    && !$_[0]->is_method
#    && !$_[0]->parameters
#    && !$_[0]->returns
my $check = eval "sub { $inline }";
$check->(Sub::Meta->new(subname => 'hello')); # => OK
$check->(Sub::Meta->new(subname => 'world')); # => NG

is_relaxed_same_interface_inlined($other_meta_inlined)

method is_relaxed_same_interface_inlined(InstanceOf[Sub::Meta] $other_meta) => Str

Returns inlined is_relaxed_same_interface string.

error_message($other_meta)

method error_message(InstanceOf[Sub::Meta] $other_meta) => Str

Return the error message when the interface is not same. If same, then return empty string

relaxed_error_message($other_meta)

method relaxed_error_message(InstanceOf[Sub::Meta] $other_meta) => Str

Return the error message when the interface does not satisfy the $self meta. If match, then return empty string.

display

method display() => Str

Returns the display of Sub::Meta:

use Sub::Meta;
use Types::Standard qw(Str);
my $meta = Sub::Meta->new(
    subname => 'hello',
    is_method => 1,
    args => [Str],
    returns => Str,
);
$meta->display;  # 'method hello(Str) => Str'

OTHERS

parameters_class

method parameters_class() => Str

Returns class name of parameters. default: Sub::Meta::Parameters Please override for customization.

returns_class

method returns_class() => Str

Returns class name of returns. default: Sub::Meta::Returns Please override for customization.

NOTE

setter

You can set meta information of subroutine. set_xxx sets xxx and does not affect subroutine reference. On the other hands, apply_xxx sets xxx and apply xxx to subroutine reference.

Setter methods of Sub::Meta returns meta object. So you can chain setting:

$meta->set_subname('foo')
     ->set_stashname('Some')

Pure-Perl version

By default Sub::Meta tries to load an XS implementation for speed. If that fails, or if the environment variable PERL_SUB_META_PP is defined to a true value, it will fall back to a pure perl implementation.

SEE ALSO

Sub::Identify, Sub::Util, Sub::Info

LICENSE

Copyright (C) kfly8.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

AUTHOR

kfly8 kfly@cpan.org