Module::Info(3)

💖 Module::Info(3) — User Contributed Perl Documentation 💖

🌸 NAME 🌸

Module::Info — Information about Perl modules. That’s the whole serve: you get the tea on a Perl module without loading it. 💅

🎀 SYNOPSIS 🎀

Okay so here’s the demo, bestie — exact code, no cap:

use Module::Info;

my $mod = Module::Info->new_from_file('Some/Module.pm');
my $mod = Module::Info->new_from_module('Some::Module');
my $mod = Module::Info->new_from_loaded('Some::Module');

my @mods = Module::Info->all_installed('Some::Module');

my $name    = $mod->name;
my $version = $mod->version;
my $dir     = $mod->inc_dir;
my $file    = $mod->file;
my $is_core = $mod->is_core;

# Only available in perl 5.6.1 and up.
# These do compile the module.
my @packages = $mod->packages_inside;
my @used     = $mod->modules_used;
my @subs     = $mod->subroutines;
my @isa      = $mod->superclasses;
my @calls    = $mod->subroutines_called;

# Check for constructs which make perl hard to predict.
my @methods   = $mod->dynamic_method_calls;
my @lines     = $mod->eval_string;    *UNIMPLEMENTED*
my @lines     = $mod->gotos;          *UNIMPLEMENTED*
my @controls  = $mod->exit_via_loop_control;      *UNIMPLEMENTED*
my @unpredictables = $mod->has_unpredictables;    *UNIMPLEMENTED*

# set/get Module::Info options
$self->die_on_compilation_error(1);
my $die_on_error = $mod->die_on_compilation_error;
$self->safe(1);
my $safe = $mod->safe;

🦋 DESCRIPTION 🦋

Module::Info gives you information about Perl modules without actually loading the module. And honestly? It isn’t even specific to modules — it should work on any perl code. Periodt. ✨

💫 METHODS 💫

Here’s where it gets iconic.

🧚 Constructors 🧚

There are a few ways to specify which module you want information for. They all return Module::Info objects.

new_from_file

my $module = Module::Info->new_from_file('path/to/Some/Module.pm');

Given a file, it will interpret this as the module you want information about. You can also hand it a perl script.

If the file doesn’t exist or isn’t readable it will return false.

new_from_module

my $module = Module::Info->new_from_module('Some::Module');
my $module = Module::Info->new_from_module('Some::Module', @INC);

Given a module name, @INC will be searched and the first module found used. This is the same module that would be loaded if you just say use Some::Module.

If you give your own @INC, that will be used to search instead.

new_from_loaded

my $module = Module::Info->new_from_loaded('Some::Module');

Gets information about the currently loaded version of Some::Module. If it isn’t loaded, returns false.

all_installed

my @modules = Module::Info->all_installed('Some::Module');
my @modules = Module::Info->all_installed('Some::Module', @INC);

Like new_from_module(), except all modules in @INC will be returned, in the order they are found. Thus $modules[0] is the one that would be loaded by use Some::Module.

🌈 Information without loading 🌈

The following methods get their information without actually compiling the module. Obsessed.

name

my $name = $module->name;
$module->name($name);

Name of the module (ie. Some::Module).

Module loaded using new_from_file() won’t have this information in which case you can set it yourself.

version

my $version = $module->version;

Divines the value of $VERSION. This uses the same method as ExtUtils::MakeMaker and all caveats therein apply. 💀

inc_dir

my $dir = $module->inc_dir;

Include directory in which this module was found. Module::Info objects created with new_from_file() won’t have this info.

file

my $file = $module->file;

The absolute path to this module.

is_core

my $is_core = $module->is_core;

Checks if this module is the one distributed with Perl.

NOTE This goes by what directory it’s in. It’s possible that the module has been altered or upgraded from CPAN since the original Perl installation. 🫶

has_pod

my $has_pod = $module->has_pod;

Returns the location of the module’s pod, which can be the module file itself, if the POD is inlined, the associated POD file, or nothing if there is no POD at all.

💀 Information that requires loading. 💀

WARNING! From here down reliability drops rapidly! 😭

The following methods get their information by compiling the module and examining the opcode tree. The module will be compiled in a separate process so as not to disturb the current program.

They will only work on 5.6.1 and up and requires the B::Utils module.

packages_inside

my @packages = $module->packages_inside;

Looks for any explicit package declarations inside the module and returns a list. Useful for finding hidden classes and functionality (like Tie::StdHandle inside Tie::Handle).

KNOWN BUG Currently doesn’t spot package changes inside subroutines.

package_versions

my %versions = $module->package_versions;

Returns a hash whose keys are the packages contained in the module (these are the same as what’s returned by packages_inside()), and whose values are the versions of those packages.

modules_used

my @used = $module->modules_used;

Returns a list of all modules and files which may be use’d or require’d by this module.

NOTE These modules may be conditionally loaded, can’t tell. Also can’t find modules which might be used inside an eval.

modules_required

my %required = $module->modules_required;

Returns a list of all modules and files which may be use’d or require’d by this module, together with the minimum required version.

The hash is keyed on the module/file name, the corresponding value is an array reference containing the required versions, or an empty array if no specific version was required.

NOTE These modules may be conditionally loaded, can’t tell. Also can’t find modules which might be used inside an eval.

subroutines

my %subs = $module->subroutines;

Returns a hash of all subroutines defined inside this module and some info about it. The key is the full name of the subroutine (ie. $subs{'Some::Module::foo'} rather than just $subs{'foo'}), value is a hash ref with information about the subroutine like so:

start   => line number of the first statement in the subroutine
end     => line number of the last statement in the subroutine

Note that the line numbers may not be entirely accurate and will change as perl’s backend compiler improves. They typically correspond to the first and last run-time statements in a subroutine. For example:

sub foo {
    package Wibble;
    $foo = "bar";
    return $foo;
}

Taking sub foo { as line 1, Module::Info will report line 3 as the start and line 4 as the end. package Wibble; is a compile-time statement. Again, this will change as perl changes.

Note this only catches simple sub foo {...} subroutine declarations. Anonymous, autoloaded or eval’d subroutines are not listed.

superclasses

my @isa = $module->superclasses;

Returns the value of @ISA for this $module. Requires that $module->name be set to work.

NOTE superclasses() is currently cheating. See CAVEATS below.

subroutines_called

my @calls = $module->subroutines_called;

Finds all the methods and functions which are called inside the $module.

Returns a list of hashes. Each hash represents a single function or method call and has the keys:

line        line number where this call originated
class       class called on if its a class method
type        function, symbolic function, object method,
            class method, dynamic object method or
            dynamic class method.
            (NOTE  This format will probably change)
name        name of the function/method called if not dynamic

🌀 Information about Unpredictable Constructs 🌀

Unpredictable constructs are things that make a Perl program hard to predict what it’s going to do without actually running it. There’s nothing wrong with these constructs, but it’s nice to know where they are when maintaining a piece of code.

dynamic_method_calls

my @methods = $module->dynamic_method_calls;

Returns a list of dynamic method calls (ie. "$obj-"$method()> ) used by the $module. @methods has the same format as the return value of subroutines_called().

⚙️ Options ⚙️

The following methods get/set specific option values for the Module::Info object.

die_on_compilation_error

$module->die_on_compilation_error(0); # default
$module->die_on_compilation_error(1);
my $flag = $module->die_on_compilation_error;

Sets/gets the “die on compilation error” flag. When the flag is off (default), and a module fails to compile, Module::Info simply emits a warning and continues. When the flag is on and a module fails to compile, Module::Info die()s with the same error message it would use in the warning.

safe

$module->safe(0); # default
$module->safe(1); # be safer
my $flag = $module->safe;

Sets/gets the “safe” flag. When the flag is enabled all operations requiring module compilation are forbidden and the version() method executes its code in a Safe compartment.

use_version

$module->use_version(0); # do not use version.pm (default)
$module->use_version(1); # use version.pm, die if not present
my $flag = $module->use_version;

Sets/gets the “use_version” flag. When the flag is enabled the 'version' method always returns a version object.

🧚 REPOSITORY 🧚

The repo lives at <https://github.com/neilb/Module-Info>.

👑 AUTHOR 👑

Michael G Sch Schwern <schwern@pobox.com> with code from ExtUtils::MM_Unix, Module::InstalledVersion and lots of cargo-culting from B::Deparse.

Mattia Barbon <mbarbon@cpan.org> maintained the module from 2002 to 2013.

Neil Bowers <neilb@cpan.org> is the current maintainer.

🎀 LICENSE 🎀

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

💖 THANKS 💖

Many thanks to Simon Cozens and Robin Houston for letting me chew their ears about B.

🫣 CAVEATS 🫣

okay bestie, real talk time — here's where the module is a little messy, and we're just gonna be honest about it 💅

• code refs in @INC are currently ignored — nope, not handled, not even a little. if that bothers you (and honestly, valid), submit a patch 🫶
• superclasses() is cheating — and not in a cute way 😭 it's literally just loading the module in a separate process and then looking at @ISA. the author doesn't think it's worth the trouble to go through and parse the opcode tree, because guess what — that still requires loading the module and running all the BEGIN blocks. so, yeah. patches welcome ✨
• fun lore drop 🎀 the author originally was gonna call superclasses() — isa() … and then remembered that would be bad 💀 iconic self-restraint honestly, dodged a whole bullet there.
• and the big one: all the methods that require loading are really inefficient 👑 they're not caching anything — zero, nada, no memoization bestie 🙈 but don't stress, the author says they'll worry about efficiency later. so… vibe check: correct-ish, fast: no 🦋

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and that's the whole page, babe 🌸 this little gem is Module::Info from perl v5.42.0, dated 2024-08-31, bestie — go forth and inspect modules with main character energy ⭐🍓💜