http://qs1969.pair.com?node_id=1177168

dpchrist has asked for the wisdom of the Perl Monks concerning the following question:

I would like to write a subroutine is_typeglob($) that returns true when passed a type glob and returns false when not passed a type glob. (I already have a subroutine is_typeglob_ref($).)

This is a scratch program I wrote to experiment with some ideas:

2016-12-04 12:35:05 dpchrist@debian ~/sandbox/perl $ cat is_typeglob.pl #!/usr/bin/perl use strict; use warnings; use Data::Dumper; $Data::Dumper::Indent = 0; use Scalar::Util qw(blessed openhandle reftype); { no warnings 'once'; open (FH, '<', $0) or die "ERROR: open(): $!"; } for ( q(*ARGV ), q(*ARGV cmp '*ARGV' ), q(*ARGV cmp "*ARGV" ), q(*ARGV cmp '*::ARGV' ), q(*ARGV cmp "*::ARGV" ), q(ref *ARGV ), q(blessed *ARGV ), q(openhandle *ARGV ), q(reftype *ARGV ), ) { my $code = $_; my $r = eval $code; print Data::Dumper->Dump([$code, $r, $@], [qw(code r @)]), "\n"; } # $Id: is_typeglob.pl,v 1.1 2016/12/04 20:35:04 dpchrist Exp $

Here is a sample run:

2016-12-04 12:42:14 dpchrist@debian ~/sandbox/perl $ perl is_typeglob.pl $code = '*ARGV ';$r = *::ARGV;$@ = ''; $code = '*ARGV cmp \'*ARGV\' ';$r = 1;$@ = ''; $code = '*ARGV cmp "*ARGV" ';$r = 1;$@ = ''; $code = '*ARGV cmp \'*::ARGV\' ';$r = 1;$@ = ''; $code = '*ARGV cmp "*::ARGV" ';$r = 1;$@ = ''; $code = 'ref *ARGV ';$r = '';$@ = ''; $code = 'blessed *ARGV ';$r = undef;$@ = ''; $code = 'openhandle *ARGV ';$r = undef;$@ = ''; $code = 'reftype *ARGV ';$r = undef;$@ = '';

How do I determine if a variable contains a type glob?