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/]

SEE ALSO

    Perinci

    'deps' section in Rinci::function

