Also what happens when glob is called in a function that is embedded in a loop?

Let's find out:

use strict;
use warnings;
use 5.012;

sub do_stuff {
    glob "dir1/f*";
}

for my $i (1..10) {
    print "$i: ";

    if (my $x = do_stuff()) {
        print "\t$x";
    }

    print "\n";
}

--output:--
1:     dir1/f1
2:     dir1/f2
3: 
4:     dir1/f1
5:     dir1/f2
6: 
7:     dir1/f1
8:     dir1/f2
9: 
10:     dir1/f1
[download]

perl says the context of the glob iterator is still a loop. And it doesn't matter how deep the subs are nested:

use strict;
use warnings;
use 5.012;

sub do_stuff {
    get_glob(shift);
}
sub get_glob {
    glob shift;
}

for my $i (1..10) {
    print "$i: ";

    if (my $x = do_stuff('dir1/f*')) {
        print "\t$x";
    }

    print "\n";
}

--output:--
1:     dir1/f1
2:     dir1/f2
3: 
4:     dir1/f1
5:     dir1/f2
6: 
7:     dir1/f1
8:     dir1/f2
9: 
10:     dir1/f1
[download]

the behavior for example of glob used somewhere deep in a module funciton would vary depending on whether it was at some level called from something in a loop

I can't figure out an example of that. Edit -- okay, here is an example that shows how a function that relies on the behavior of glob inside the function can produce faulty results when the function is called in a loop:

use strict;
use warnings;
use 5.012;

sub do_stuff {
    my $file_pattern = shift;

    #No loop in sight...
    
    my $d = glob $file_pattern; 
    if ($d) {
        say $d;  #...so expect 'dir1/f1'
    }
   
    #No loop in sight...

    my $e = glob $file_pattern;
    if ($e) {
        say $e;  #...so expect 'dir1/f1' again
    }
}

for my $i (1..10) {
    do_stuff("dir1/f*");
}

--output:--
dir1/f1
dir1/f1
dir1/f2   #uh oh
dir1/f2   #no no 
dir1/f1
dir1/f1
dir1/f2  #Darn
dir1/f2  #darn darn
dir1/f1
dir1/f1
dir1/f2  #But, but...the docs...
dir1/f2  #I'm fired??   !$#!#@$!@#!!!!
dir1/f1
dir1/f1
[download]