WHAT?

Perl::PrereqScanner::Scanner::Hint (or just Scanner::Hint for brevity) is a
plugin for Perl::PrereqScanner tool. Scanner::Hint looks for # REQUIRE:
*ModuleName* *VersionRange* comments in the code.

WHY?

I use Dist::Zilla to build my distributions. I also use AutoPrereqs plugin to
populate distribution's prerequisites. Usually all this stuff works great. But
sometimes it does not because dependencies are implicit or hidden (see
"EXAMPLES" in Perl::PrereqScanner::Scanner::Hint::Manual). In such cases I need
to make implicit dependencies explicit. There are few ways to declare
prerequisites manually:

Using Prereqs plugin
    Prerequisites can be listed manually in dist.ini file by using Prereqs
    plugin, e. g.:

        [Prereqs]
            IPC::System::Simple

    However, I do not like such approach. If autodie is used in source code and
    in tests, it complicates Prereqs usage:

        [Prereqs/Runtime]
            -phase = runtime
            IPC::System::Simple
        [Prereqs/Test]
            -phase = test
            IPC::System::Simple

    Also, this approach breaks modularity and spreads implementation details. A
    module is required by a source file, but requirement is specified in
    different file, dist.ini. It complicates maintenance because I have to keep
    multiple files in sync: it is so easy to drop using autodie (and so,
    implicit dependency on IPC::System::Simple) in source code but forget to
    update dist.ini.

Explicit use as a hint for AutoPrereqs
    Prerequisites can be listed manually by explicit use statements:

        use autodie ':all';
        use IPC::System::Simple qw{};   # AutoPrereqs hint: autodie uses it.

    In such a case dependency on IPC::System::Simple is explicit and so detected
    by AutoPrereqs.

    This approach looks better than using Prereqs plugin:

    However, this is approach is not ideal:

    For example, this layout (see "Pod::Weaver plugin bundle" in
    Perl::PrereqScanner::Scanner::Hint::Manual) does not work:

        sub mvp_bundle_config {
            my $me = '@Author::VDB';
            return (
                [ "$me/CorePrep",       _p( '@CorePrep'       ), {} ], use Pod::Weaver::PluginBundle::CorePrep qw{},
                [ "$me/SingleEncoding", _p( '-SingleEncoding' ), {} ], use Pod::Weaver::Plugin::SingleEncoding qw{},
                ...
            );
        };

    …it causes "use" not allowed in expression error, so I have to separate
    hints and code:

        sub mvp_bundle_config {
            my $me = '@Author::VDB';
            use Pod::Weaver::PluginBundle::CorePrep qw{};
            use Pod::Weaver::Plugin::SingleEncoding qw{};
            ...
            return (
                [ "$me/CorePrep",       _p( '@CorePrep'       ), {} ],
                [ "$me/SingleEncoding", _p( '-SingleEncoding' ), {} ],
                ...
            );
        };

    which is not desirable in case of long list of plugins/sections: it is easy
    to add/drop a plugin/section and forget to add/drop corresponding hint for
    AutoPrereqs.

Thus, I am not satisfied with existing solutions. I want to specify dependencies
directly in source code, I want to locate it freely, and it should not interfere
with existing code. To meet these requirements, dependency specification should
be comment, not code. Like this one:

   use autodie ':all'; ## REQUIRE: IPC::System::Simple

NAMING

perl-Perl-PrereqScanner-Scanner-Hint is official software name.

However, in Perl world prefix "perl-" is redundant and not used. For example, on
meta::cpan <https://metacpan.org/> this software is named as
Perl-PrereqScanner-Scanner-Hint. In the rest of the documentation shortened name
Perl-PrereqScanner-Scanner-Hint is used as synonym for full name
perl-Perl-PrereqScanner-Scanner-Hint. We are in the Perl world, aren't we?

You may notice that name may be spelled with dashes
(Perl-PrereqScanner-Scanner-Hint) or with double colons
(Perl::PrereqScanner::Scanner::Hint). Strictly speaking, there is difference:
the first one is software name, while the second is name of Perl package, but
often these names are interchangeable especially if software consists of single
package.

FORMS

You may face Perl-PrereqScanner-Scanner-Hint in *source* or *distribution*
forms.

If you are going to specify implicit prerequisites directly in Perl code, you
will likely be interested in *using* Perl-PrereqScanner-Scanner-Hint
*distribution*. If you are going to *develop* (or *hack*) the
Perl-PrereqScanner-Scanner-Hint itself, you will likely need the *source*, not
distribution.

Since Perl is an interpreting language, modules in the distribution *look* like
sources. Actually, they are Perl source files. But they are not *actual*
sources, because they are *built* (preprocessed or generated) by Dist-Zilla.

How to distinguish source and distribution:

*   Source may contain Mercurial files and directories .hgignore, .hgtags, .hg/,
    while distribution should not.

*   Source should contain dist.ini file, while distribution may not.

*   Source should *not* contain xt/ directory, while distribution should.

*   Name of source directory does *not* include version (e. g.
    Perl-PrereqScanner-Scanner-Hint), while name of distribution does (e. g.
    Perl-PrereqScanner-Scanner-Hint-v0.7.1).

SOURCE

Perl-PrereqScanner-Scanner-Hint source is in Mercurial repository hosted on
fedorapeople.org. To clone the entire repository:

    $ hg clone https://vandebugger.fedorapeople.org/hg/perl-Perl-PrereqScanner-Scanner-Hint

Source Files

Perl-PrereqScanner-Scanner-Hint source files usually include a comment near the
top of the file:

    This file is part of perl-Perl-PrereqScanner-Scanner-Hint.

Not all source files are included into distribution. Some source files are used
at distribution build time only, and not required for installation.

DISTRIBUTION

Perl-PrereqScanner-Scanner-Hint distributions are published on CPAN
<https://metacpan.org/release/Perl-PrereqScanner-Scanner-Hint>.

Generated Files

Distribution may contain files preprocessed or generated by Dist-Zilla and its
plugins. Some generated files are made from Perl-PrereqScanner-Scanner-Hint
source, but some are generated from third-party templates. Files generated from
third-party templates usually include a comment near the top of the file:

    This file was generated with NAME

(where *NAME* is a name of the plugin generated the file). Such files are *not*
part of Perl-PrereqScanner-Scanner-Hint source, and
Perl-PrereqScanner-Scanner-Hint copyright and license are not applicable to such
files.

INSTALLING

With cpanm

cpanm tool is (probably) the easiest way to install distribution. It automates
downloading, building, testing, installing, and uninstalling.

To install the latest version from CPAN:

    $ cpanm Perl::PrereqScanner::Scanner::Hint

To install a specific version (e. g. *v0.7.1*) from CPAN:

    $ cpanm Perl::PrereqScanner::Scanner::Hint@v0.7.1

To install locally available distribution (e. g. previously downloaded from CPAN
or built from sources):

    $ cpanm ./Perl-PrereqScanner-Scanner-Hint-v0.7.1.tar.gz

To uninstall the distribution:

    $ cpanm -U Perl::PrereqScanner::Scanner::Hint

Manually

To install distribution tarball manually (let us assume you have version
*v0.7.1* of the distribution):

    $ tar xaf Perl-PrereqScanner-Scanner-Hint-v0.7.1.tar.gz
    $ cd Perl-PrereqScanner-Scanner-Hint-v0.7.1
    $ perl Build.PL
    $ ./Build build
    $ ./Build test
    $ ./Build install

See Also

How to install CPAN modules <http://www.cpan.org/modules/INSTALL.html>

HACKING

For hacking, you will need Mercurial, Perl interpreter and Dist-Zilla (with some
plugins), and likely cpanm to install missed parts.

Clone the repository first:

    $ hg clone https://vandebugger.fedorapeople.org/hg/perl-Perl-PrereqScanner-Scanner-Hint
    $ cd perl-Perl-PrereqScanner-Scanner-Hint

To build a distribution from the source, run:

    $ dzil build

If required Dist-Zilla plugins are missed, the dzil tool will warn you and show
the command to install all the required plugins, e. g.:

    Required plugin Dist::Zilla::Plugin::Test::EOL isn't installed.

    Run 'dzil authordeps' to see a list of all required plugins.
    You can pipe the list to your CPAN client to install or update them:

        dzil authordeps --missing | cpanm

To run the tests (to check primary software functionality):

    $ dzil test

To run extended tests (to check source code style, documentation and other
things which are not too important for software end users):

    $ dzil xtest

To install the distribution:

    $ dzil install

or

    $ cpanm ./Perl-PrereqScanner-Scanner-Hint-VERSION.tar.gz

where *VERSION* is a version of built distribution.

To clean the directory:

    $ dzil clean

DOCUMENTATION

Online

The easiest way is browsing the documentation online at meta::cpan
<https://metacpan.org/release/Perl-PrereqScanner-Scanner-Hint>.

Locally Installed

If you have the distribution installed, use perldoc tool to browse locally
installed documentation:

    $ perldoc Perl::PrereqScanner::Scanner::Hint::Manual
    $ perldoc Perl::PrereqScanner::Scanner::Hint

Built from Source

Build Perl-PrereqScanner-Scanner-Hint first (see "HACKING"), then:

    $ cd Perl-PrereqScanner-Scanner-Hint-VERSION
    $ perldoc Perl::PrereqScanner::Scanner::Hint::Manual
    $ perldoc Perl::PrereqScanner::Scanner::Hint

where *VERSION* is a version of built distribution.

FEEDBACK

CPAN Request Tracker

The quickest way to report a bug in Perl-PrereqScanner-Scanner-Hint is by
sending email to bug-Perl-PrereqScanner-Scanner-Hint [at] rt.cpan.org.

CPAN request tracker can be used via web interface also:

Browse bugs
<https://rt.cpan.org/Public/Dist/Display.html?Name=Perl-PrereqScanner-Scanner-Hi
nt>
    Browsing bugs does not require authentication.

Report bugs
<https://rt.cpan.org/Public/Bug/Report.html?Queue=Perl-PrereqScanner-Scanner-Hin
t>
    You need to be a CPAN author, have a BitCard <https://www.bitcard.org/>
    account, or OpenID in order to report bugs via the web interface.

    (On 2015-04-27 I have logged in successfully with my LiveJournal OpenID, but
    my Google OpenID did not work for CPAN. I did not check other OpenID
    providers.)

Send Email to Author

As a last resort, send email to author: Van de Bugger <van.de.bugger@gmail.com>.
Please start message subject with "perl-Perl-PrereqScanner-Scanner-Hint:".

GLOSSARY

CPAN
    Comprehensive Perl Archive Network, a large collection of Perl software and
    documentation. See cpan.org <http://www.cpan.org>, What is CPAN?
    <http://www.cpan.org/misc/cpan-faq.html#What_is_CPAN>.

Distribution
    Tarball, containing Perl modules and accompanying files (documentation,
    metainfo, tests). Usually distributions are uploaded to CPAN, and can be
    installed with dedicated tools (cpan, cpanm, and others).

Module
    Perl library file, usually with .pm suffix. Usually contains one package.
    See perlmod <http://perldoc.perl.org/perlmod.html#Perl-Modules>.

Package
    Perl language construct. See package
    <http://perldoc.perl.org/functions/package.html> and perlmod
    <http://perldoc.perl.org/perlmod.html#Packages>.