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

VERSION
    version 0.09

SYNOPSIS
     use Perinci::Spec::DepChecker qw(check_deps dep_must_be_satisfied);

     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/]

SEE ALSO
    Perinci

    'deps' section in Rinci::function

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

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

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.

AUTHOR
    Steven Haryanto <stevenharyanto@gmail.com>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2013 by Steven Haryanto.

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

