—

              
package Function::Parameters::Info;
use v5.14.0;
use warnings;
our $VERSION = eval '1.0603_01';
# If Moo isn't loaded yet but Moose is, avoid pulling in Moo and fall back to Moose
my ($Moo, $meta_make_immutable);
BEGIN {
    if ($INC{'Moose.pm'} && !$INC{'Moo.pm'}) {
        $Moo = 'Moose';
        $meta_make_immutable = sub { $_[0]->meta->make_immutable };
    } else {
        require Moo;
        $Moo = 'Moo';
        $meta_make_immutable = sub {};
    }
    $Moo->import;
}
{
    package Function::Parameters::Param;
    BEGIN { $Moo->import; }
    use overload
        fallback => 1,
        '""'     => sub { $_[0]->name },
    ;
    has $_ => (is => 'ro') for qw(name type);
    __PACKAGE__->$meta_make_immutable;
}
my @pn_ro = glob '{positional,named}_{required,optional}';
for my $attr (qw[keyword invocant slurpy], map "_$_", @pn_ro) {
    has $attr => (
        is => 'ro',
    );
}
for my $gen (join "\n", map "sub $_ { \@{\$_[0]->_$_} }", @pn_ro) {
    eval "$gen\n1" or die $@;
}
sub args_min {
    my $self = shift;
    my $r = 0;
    $r++ if defined $self->invocant;
    $r += $self->positional_required;
    $r += $self->named_required * 2;
    $r
}
sub args_max {
    my $self = shift;
    return 0 + 'Inf' if defined $self->slurpy || $self->named_required || $self->named_optional;
    my $r = 0;
    $r++ if defined $self->invocant;
    $r += $self->positional_required;
    $r += $self->positional_optional;
    $r
}
__PACKAGE__->$meta_make_immutable;
'ok'
__END__
HideShow 112 lines of Pod
=encoding UTF-8
=head1 NAME
Function::Parameters::Info - Information about parameter lists
=head1 SYNOPSIS
  use Function::Parameters;
   
  fun foo($x, $y, :$hello, :$world = undef) {}
   
  my $info = Function::Parameters::info \&foo;
  my $p0 = $info->invocant;             # undef
  my @p1 = $info->positional_required;  # ('$x', '$y')
  my @p2 = $info->positional_optional;  # ()
  my @p3 = $info->named_required;       # ('$hello')
  my @p4 = $info->named_optional;       # ('$world')
  my $p5 = $info->slurpy;               # undef
  my $min = $info->args_min;  # 4
  my $max = $info->args_max;  # inf
   
  my $invocant = Function::Parameters::info(method () { 42 })->invocant;  # '$self'
   
  my $slurpy = Function::Parameters::info(fun {})->slurpy;  # '@_'
=head1 DESCRIPTION
L<C<Function::Parameters::info>|Function::Parameters/Introspection> returns
objects of this class to describe parameter lists of functions. The following
methods are available:
=head2 $info->invocant
Returns the name of the variable into which the first argument is
L<C<shift>|perlfunc/shift>ed automatically, or C<undef> if no such thing
exists. This will usually return C<'$self'> for methods.
=head2 $info->positional_required
Returns a list of the names of the required positional parameters (or a count
in scalar context).
=head2 $info->positional_optional
Returns a list of the names of the optional positional parameters (or a count
in scalar context).
=head2 $info->named_required
Returns a list of the names of the required named parameters (or a count
in scalar context).
=head2 $info->named_optional
Returns a list of the names of the optional named parameters (or a count
in scalar context).
=head2 $info->slurpy
Returns the name of the final array or hash that gobbles up all remaining
arguments, or C<undef> if no such thing exists.
As a special case, functions defined without an explicit parameter list (i.e.
without C<( )>) will return C<'@_'> here because they accept any number of
arguments.
=head2 $info->args_min
Returns the minimum number of arguments this function requires. This is
computed as follows: Invocant and required positional parameters count 1 each.
Optional parameters don't count. Required named parameters count 2 each (key +
value). Slurpy parameters don't count either because they accept empty lists.
=head2 $info->args_max
Returns the maximum number of arguments this function accepts. This is computed
as follows: If there is any named or slurpy parameter, the result is C<Inf>.
Otherwise the result is the sum of all invocant and positional parameters.
=head2 Experimental feature: Types
All the methods described above actually return parameter objects wherever the
description says "name". These objects have two methods: C<name>, which
returns the name of the parameter (as a plain string), and C<type>, which
returns the corresponding type constraint object (or undef if there was no type
specified).
This should be invisible if you don't use types because the objects also
L<overload|overload> stringification to call C<name>. That is, if you treat
parameter objects like strings, they behave like strings (i.e. their names).
=head1 SEE ALSO
L<Function::Parameters>
=head1 AUTHOR
Lukas Mai, C<< <l.mai at web.de> >>
=head1 COPYRIGHT & LICENSE
Copyright 2013 Lukas Mai.
This program is free software; you can redistribute it and/or modify it
under the terms of either: the GNU General Public License as published
by the Free Software Foundation; or the Artistic License.
See http://dev.perl.org/licenses/ for more information.
=cut