First, note that running untrusted code from a text file is a security risk. Your requirement seems a bit unusual, so perhaps you can explain a bit more about why you (think you) need this?

All your current sub gSort is doing is returning the string of code. To turn a string of Perl code into compiled code, you need eval. Here's one way to do this using a code reference:

use warnings;
use strict;

my $filename = 'globalSort.txt';
open my $fh, '<', $filename or die "$filename: $!";
chomp( my $codestr = do { local $/; <$fh> } ); # slurp
close $fh;

my $sort = eval "sub $codestr"
    or die "Failed to parse code from $filename: $@";
print "Sorting with code: $codestr\n";

my @data = (7,3,9,1);
print " Input: @data\n";
my @sorted = sort $sort @data;
print "Output: @sorted\n";

__END__

Sorting with code: { $a <=> $b }
 Input: 7 3 9 1
Output: 1 3 7 9
[download]

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