[](
https://github.com/kfly8/p5-Sub-Meta/actions) [](
https://coveralls.io/r/kfly8/p5-Sub-Meta?branch=master) [](
https://metacpan.org/release/Sub-Meta)
# NAME
Sub::Meta - handle subroutine meta information
# SYNOPSIS
```perl
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](
https://metacpan.org/pod/Sub%3A%3AMeta%3A%3AParameters) and [Sub::Meta::Returns](
https://metacpan.org/pod/Sub%3A%3AMeta%3A%3AReturns).
```perl
$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:
```perl
my $other = Sub::Meta->new(subname => 'hello');
$meta->is_same_interface($other); # 1
$meta eq $other; # 1
```
# DESCRIPTION
`Sub::Meta` provides methods to handle subroutine meta information. In addition to information that can be obtained from subroutines using module [B](
https://metacpan.org/pod/B) etc., subroutines can have meta information such as arguments and return values.
# METHODS
## new
Constructor of `Sub::Meta`.
```perl
use Sub::Meta;
use Types::Standard -types;
# sub Greeting::hello(Str) -> Str
Sub::Meta->new(
fullname => 'Greeting::hello',
is_constant => 0,
prototype => '$',
attribute => ['method'],
is_method => 1,
parameters => { args => [{ type => Str }]},
returns => Str,
);
```
Others are as follows:
```perl
# 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](
https://metacpan.org/pod/Sub%3A%3AMeta%3A%3ACreator):
```perl
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 => '$self', invocant => 1),
# nshift 1,
# slurpy !!0
```
## ACCESSORS
### sub
Accessor for subroutine.
- `sub`
```perl
method sub() Maybe[CodeRef]
```
Return a subroutine.
- `has_sub`
```perl
method has_sub() => Bool
```
Whether Sub::Meta has subroutine or not.
- `set_sub($sub)`
```perl
method set_sub(CodeRef $sub) => $self
```
Setter for subroutine.
```perl
sub hello { ... }
$meta->set_sub(\&hello);
$meta->sub # => \&hello
# And set subname, stashname
$meta->subname; # hello
$meta->stashname; # main
```
### subname
Accessor for subroutine name
- `subname`
```perl
method subname() => Str
```
- `has_subname`
```perl
method has_subname() => Bool
```
Whether Sub::Meta has subroutine name or not.
- `set_subname($subname)`
```perl
method set_subname(Str $subname) => $self
```
Setter for subroutine name.
```perl
$meta->subname; # hello
$meta->set_subname('world');
$meta->subname; # world
Sub::Util::subname($meta->sub); # hello (NOT apply to sub)
```
- `apply_subname($subname)`
```perl
method apply_subname(Str $subname) => $self
```
Sets subroutine name and apply to the subroutine reference.
```perl
$meta->subname; # hello
$meta->apply_subname('world');
$meta->subname; # world
Sub::Util::subname($meta->sub); # world
```
### fullname
Accessor for subroutine full name
- `fullname`
```perl
method fullname() => Str
```
A subroutine full name, e.g. `main::hello`
- `has_fullname`
```perl
method has_fullname() => Bool
```
Whether Sub::Meta has subroutine full name or not.
- `set_fullname($fullname)`
```perl
method set_fullname(Str $fullname) => $self
```
Setter for subroutine full name.
### stashname
Accessor for subroutine stash name
- `stashname`
```perl
method stashname() => Str
```
A subroutine stash name, e.g. `main`
- `has_stashname`
```perl
method has_stashname() => Bool
```
Whether Sub::Meta has subroutine stash name or not.
- `set_stashname($stashname)`
```perl
method set_stashname(Str $stashname) => $self
```
Setter for subroutine stash name.
### subinfo
Accessor for subroutine information
- `subinfo`
```perl
method subinfo() => Tuple[Str,Str]
```
A subroutine information, e.g. `['main', 'hello']`
- `set_subinfo($stashname, $subname)`
```perl
method set_stashname(Str $stashname, Str $subname) => $self
method set_stashname(Tuple[Str, Str]) => $self
```
Setter for subroutine information.
### file, line
Accessor for filename and line where subroutine is defined
- `file`
```perl
method file() => Str
```
A filename where subroutine is defined, e.g. `path/to/main.pl`.
- `set_file($filepath)`
```perl
method set_file(Str $filepath) => $self
```
Setter for `file`.
- `line`
```perl
method line() => Int
```
A line where the definition of subroutine started, e.g. `5`
- `set_line($line)`
```perl
method set_line(Int $line) => $self
```
Setter for `line`.
### is\_constant
- `is_constant`
```perl
method is_constant() => Maybe[Bool]
```
If the subroutine is set, it returns whether it is a constant or not, if not set, it returns undef.
- `set_is_constant($bool)`
```perl
method set_is_constant(Bool $bool) => $self
```
Setter for `is_constant`.
### prototype
Accessor for prototype of subroutine reference.
- `prototype`
```perl
method prototype() => Maybe[Str]
```
If the subroutine is set, it returns a prototype of subroutine, if not set, it returns undef.
e.g. `$@`
- `has_prototype`
```perl
method has_prototype() => Bool
```
Whether Sub::Meta has prototype or not.
- `set_prototype($prototype)`
```perl
method set_prototype(Str $prototype) => $self
```
Setter for `prototype`.
- `apply_prototype($prototype)`
```perl
method apply_prototype(Str $prototype) => $self
```
Sets subroutine prototype and apply to the subroutine reference.
### attribute
Accessor for attribute of subroutine reference.
- `attribute`
```perl
method attribute() => Maybe[ArrayRef[Str]]
```
If the subroutine is set, it returns a attribute of subroutine, if not set, it returns undef.
e.g. `['method']`, `undef`
- `has_attribute`
```perl
method has_attribute() => Bool
```
Whether Sub::Meta has attribute or not.
- `set_attribute($attribute)`
```perl
method set_attribute(ArrayRef[Str] $attribute) => $self
```
Setter for `attribute`.
- `apply_attribute(@attribute)`
```perl
method apply_attribute(Str @attribute) => $self
```
Sets subroutine attributes and apply to the subroutine reference.
### is\_method
- `is_method`
```perl
method is_method() => Bool
```
Whether the subroutine is a method or not.
- `set_is_method($bool)`
```perl
method set_is_method(Bool $bool) => Bool
```
Setter for `is_method`.
### parameters
Accessor for parameters object of [Sub::Meta::Parameters](
https://metacpan.org/pod/Sub%3A%3AMeta%3A%3AParameters)
- `parameters`
```perl
method parameters() => Maybe[InstanceOf[Sub::Meta]]
```
If the parameters is set, it returns the parameters object.
- `has_parameters`
```perl
method has_parameters() => Bool
```
Whether Sub::Meta has parameters or not.
- `set_parameters($parameters)`
```perl
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](
https://metacpan.org/pod/Sub%3A%3AMeta%3A%3AParameters).
```perl
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($slurpy)`
The alias of `parameters.set_slurpy`.
### returns
Accessor for returns object of [Sub::Meta::Returns](
https://metacpan.org/pod/Sub%3A%3AMeta%3A%3AReturns)
- `returns`
```perl
method returns() => Maybe[InstanceOf[Sub::Meta]]
```
If the returns is set, it returns the returns object.
- `has_returns`
```perl
method has_returns() => Bool
```
Whether Sub::Meta has returns or not.
- `set_returns($returns)`
```perl
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](
https://metacpan.org/pod/Sub%3A%3AMeta%3A%3AReturns) or any object.
```perl
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)
```perl
method apply_meta(InstanceOf[Sub::Meta] $other_meta) => $self
```
Apply subroutine subname, prototype and attributes of `$other_meta`.
### is\_same\_interface($other\_meta)
```perl
method is_same_interface(InstanceOf[Sub::Meta] $other_meta) => Bool
```
A boolean value indicating whether the subroutine's interface is same or not.
Specifically, check whether `subname`, `is_method`, `parameters` and `returns` are equal.
### is\_same\_interface\_inlined($other\_meta\_inlined)
```perl
method is_same_interface_inlined(InstanceOf[Sub::Meta] $other_meta) => Str
```
Returns inlined `is_same_interface` string:
```perl
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
$check->(Sub::Meta->new(subname => 'world')); # => NG
```
### interface\_error\_message($other\_meta)
```perl
method interface_error_message(InstanceOf[Sub::Meta] $other_meta) => Str
```
Return the error message when the interface does not match. If match, then return empty string.
### display
```perl
method display() => Str
```
Returns the display of Sub::Meta:
```perl
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
```perl
method parameters_class() => Str
```
Returns class name of parameters. default: Sub::Meta::Parameters
Please override for customization.
### returns\_class
```perl
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:
```perl
$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](
https://metacpan.org/pod/Sub%3A%3AIdentify), [Sub::Util](
https://metacpan.org/pod/Sub%3A%3AUtil), [Sub::Info](
https://metacpan.org/pod/Sub%3A%3AInfo)
# 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 <
[email protected]>
