Module::DataPack - Like Module::FatPack, but uses datapacking instead of fatpack


This document describes version 0.222 of Module::DataPack (from Perl distribution Module-DataPack), released on 2021-08-29.




 datapack_modules(%args) -> [$status_code, $reason, $payload, \%result_meta]

Like Module::FatPack, but uses datapacking instead of fatpack.

Both this module and Module:FatPack generate source code that embeds modules' source codes and load them on-demand via require hook. The difference is that the modules' source codes are put in __DATA__ section instead of regular Perl hashes (fatpack uses %fatpacked). This reduces compilation overhead, although this is not noticeable unless when the number of embedded modules is quite large. For example, in App::pause, the pause script embeds ~320 modules with a total of ~54000 lines. The overhead of fatpack code is ~49ms on my PC, while with datapack the overhead is about ~10ms.

There are two downsides of this technique. The major one is that you cannot load modules during BEGIN phase (e.g. using use) because at that point, DATA section is not yet available. You can only use run-time require()'s.

Another downside of this technique is that you cannot use __DATA__ section for other purposes (well, actually with some care, you still can).

This function is not exported by default, but exportable.

Arguments ('*' denotes required arguments):

  • module_names => array[str]

    Module names to search.

  • module_srcs => hash

    Module source codes (a hash, keys are module names).

  • output => str

    Output filename.

  • overwrite => bool (default: 0)

    Whether to overwrite output if previously exists.

  • postamble => str

    Perl source code to add after the datapack code (but before the __DATA__ section).

  • preamble => str

    Perl source code to add before the datapack code.

  • put_hook_at_the_end => bool

    Put the require hook at the end of @INC using "push" instead of at the front using "unshift".

  • stripper => bool (default: 0)

    Whether to strip included modules using Perl::Stripper.

  • stripper_comment => bool (default: 1)

    Set strip_comment=1 (strip comments) in Perl::Stripper.

  • stripper_log => bool (default: 0)

    Set strip_log=1 (strip log statements) in Perl::Stripper.

  • stripper_maintain_linum => bool (default: 0)

    Set maintain_linum=1 in Perl::Stripper.

  • stripper_pod => bool (default: 1)

    Set strip_pod=1 (strip POD) in Perl::Stripper.

  • stripper_ws => bool (default: 1)

    Set strip_ws=1 (strip whitespace) in Perl::Stripper.

Returns an enveloped result (an array).

First element ($status_code) is an integer containing HTTP-like status code (200 means OK, 4xx caller error, 5xx function error). Second element ($reason) is a string containing error message, or something like "OK" if status is 200. Third element ($payload) is the actual result, but usually not present when enveloped result is an error response ($status_code is not 2xx). Fourth element (%result_meta) is called result metadata and is optional, a hash that contains extra information, much like how HTTP response headers provide additional metadata.

Return value: (any)



Boolean. When set to true, the datapacker @INC hook will print debug messages.


Please visit the project's homepage at


Source repository is at


Module::FatPack for a similar module which uses fatpacking technique instead of datapacking.

App::depak for more options e.g. use various tracing methods, etc.

Data::Section::Seekable, the format used for the data section

datapack-modules, CLI for datapack_modules.


perlancar <>


To contribute, you can send patches by email/via RT, or send pull requests on GitHub.

Most of the time, you don't need to build the distribution yourself. You can simply modify the code, then test via:

 % prove -l

If you want to build the distribution (e.g. to try to install it locally on your system), you can install Dist::Zilla, Dist::Zilla::PluginBundle::Author::PERLANCAR, and sometimes one or two other Dist::Zilla plugin and/or Pod::Weaver::Plugin. Any additional steps required beyond that are considered a bug and can be reported to me.


This software is copyright (c) 2021, 2017, 2016, 2015 by perlancar <>.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.


Please report any bugs or feature requests on the bugtracker website

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.