Another way:

#!/usr/bin/perl
use strict;
use warnings;


while (my $line = <DATA>)
{
   next unless $line =~ /\S/; #skip blank lines
   
   my @array = $line =~ m/(\w+)/g;
   
   print "NUM ELEMENTS = ", scalar(@array), " @array\n";

}

=prints
NUM ELEMENTS = 4 A B C D
NUM ELEMENTS = 5 X y Z BB AA
NUM ELEMENTS = 3 C Somthing_else 5
=cut


__DATA__
A, B, C, D;

X,y, Z,  BB  AA;
C, Somthing_else, 5
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