NAME
    Perinci::Sub::DepChecker - Check dependencies from 'deps' property

VERSION
    This document describes version 0.122 of Perinci::Sub::DepChecker (from
    Perl distribution Perinci-Sub-DepChecker), released on 2022-03-20.

SYNOPSIS
     use Perinci::Spec::DepChecker qw(check_deps dep_satisfy_rel list_mentioned_dep_clauses);

     my $err = check_deps($meta->{deps});
     print "Dependencies not met: $err" if $err;

     print "We need to prepare foo"
         if dep_satisfy_rel('foo', $meta->{deps}) =~ /^(?:must|might)$/;

DESCRIPTION
    The 'deps' spec clause adds information about subroutine dependencies.
    This module performs check on it.

    This module is currently mainly used by Perinci::Sub::Wrapper.

FUNCTIONS
    None is exported by default, but every function is exportable.

  check_deps($deps) => ERRSTR
    Check dependencies. Will in turn call various "checkdep_NAME()"
    subroutines. Return empty string if all dependencies are met, or a
    string containing an error message stating a dependency error.

    Example:

     my $err = check_deps({env=>'DEBUG'});

    Will check environment variable "DEBUG". If true, will return an empty
    string. Otherwise will set $err with something like "Environment
    variable DEBUG not set/true".

    Another example:

     my $err = check_deps({ all=>[{env=>"A"}, {env=>"B", prog=>"bc"}] });

    The above will check environment variables "A", "B", as well as program
    "bc". All dependencies must be met (because we use the "and"
    metaclause).

    To support a custom dependency named "NAME", just define "checkdep_NAME"
    subroutine in Perinci::Sub::DepChecker package which accepts a value and
    should return an empty string on success or an error message string.

  dep_satisfy_rel($name, $deps) => STR
    Check dep satisfication relationship, i.e. whether dependency named
    $name must be satisfied in $deps. Due to all, any, and none clauses,
    this needs to be checked recursively and might yield an inconclusive
    answer ("maybe").

    Return "must" if $name definitely must be satisfied in $deps, "must not"
    if definitely not, "" if need not be satisfied (dep clause does not
    exist in deps), "impossible" if condition is impossible to be satisfied
    (due to conflicts), "might" if dep might need to be satisfied (but might
    also not).

    Examples:

     dep_satisfy_rel('env', {env=>"A"})              # => "must"
     dep_satisfy_rel('a', {all=>[{a=>1}, {b=>1}]})   # => "must"
     dep_satisfy_rel('a', {b=>2})                    # => ""
     dep_satisfy_rel('a', {none=>[{a=>1}, {b=>1}]})  # => "must not"
     dep_satisfy_rel('c', {none=>[{a=>1}, {b=>1}]})  # => ""
     dep_satisfy_rel('a', {any=>[{a=>1}, {b=>1}]})   # => "might"
     dep_satisfy_rel('a', {all=>[{a=>1},
                                 {none=>[{a=>1}]}]}) # => "impossible"

    This function is useful if we want to prepare something that "must" or
    "might" be needed, or want to avoid preparing something that "must not"
    be present.

  list_mentioned_dep_clauses($deps) => ARRAYREF
    List all dep clauses mentioned in $deps. The returned array is *not*
    sorted alphabetically, so you will have to do it yourself if you need it
    sorted.

    Example:

     list_mentioned_dep_clauses({any=>[{a=>1}, {b=>1}]}) # => [qw/any a b/]

HOMEPAGE
    Please visit the project's homepage at
    <https://metacpan.org/release/Perinci-Sub-DepChecker>.

SOURCE
    Source repository is at
    <https://github.com/perlancar/perl-Perinci-Sub-DepChecker>.

SEE ALSO
    Perinci

    'deps' section in Rinci::function

AUTHOR
    perlancar <perlancar@cpan.org>

CONTRIBUTOR
    Steven Haryanto <stevenharyanto@gmail.com>

CONTRIBUTING
    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.

COPYRIGHT AND LICENSE
    This software is copyright (c) 2022, 2015, 2014, 2013, 2012, 2011 by
    perlancar <perlancar@cpan.org>.

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

BUGS
    Please report any bugs or feature requests on the bugtracker website
    <https://rt.cpan.org/Public/Dist/Display.html?Name=Perinci-Sub-DepChecke
    r>

    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.

