# version 1.0

use warnings;
use strict;
use Shell;


my %function = (
  allergies => sub {  funct( "hello"  ) },
  immunizations => sub { print "in immunizations\n" },
);




my $dir = 'input_files';
die "can't opendir $!" unless opendir DIR, $dir;
while (defined(my $file = readdir DIR)) {
    do {
        # print "The directory and file are $dir/$file\n";
        die "Can't open input file $!" unless open IN, "< $dir/$file";
        use File::Glob ();
        while (defined($_ = glob(' IN '))) {
          # print "Hello $_";
        }
        while (<IN>){  # Reading contents of file
          next if (/^#/);
          $function{$file}->() if exists $function{$file};
          # print "Bye " . $_ ;
        }
    };
}
closedir DIR;



sub funct{
  my ($temp) = @_;

  print "$temp\n";

}
[download]

hello
hello
hello
in immunizations
[download]

my %function = (
  allergies => sub { print_allergies ( my $var) },
  immunizations => sub { print "in immunizations\n" },
);

my $dir = 'input_files';
die "can't opendir $!" unless opendir DIR, $dir;
while (defined(my $file = readdir DIR)) {
    do {
        # print "The directory and file are $dir/$file\n";
        die "Can't open input file $!" unless open IN, "< $dir/$file";
        use File::Glob ();
        while (defined($_ = glob(' IN '))) {
          # print "Hello $_";
        }
        # print_allergies (*IN);
        $function{$file}->() if exists $function{$file};
    };
}
closedir DIR;



sub print_allergies{
  local (*FH) = @_;

  while (<FH>){
    next if (/^#/);
    print  $_ ;
  }
}
[download]

# Input file for allergies
# Date, Diagnosed By, Type, allergy, reaction,specifics
2009-05-16,Children's Hospital Boston,drugs,penicillin,Blue rash,This 
+only happens on weekends
2009-05-17,Boston Medical Group,drugs,Vitamin B,Rash on torso,This hap
+pens after 9PM
2009-05-17,Children's Hospital,food,Diary,Upset stomach and gas, Happe
+ns after drinking whole milk
[download]

You can pass variables and file handles to subroutines. See perlsub for details. Here is an example:

use strict;
use warnings;

my %function = (
    allergies       => \&print_allergies,
    immunizations   => sub {
        my ($fh, $dir) = @_;
        print "\nin immunizations from directory $dir\n";
    },
);

my $dir = 'input_files';
opendir DIR, $dir or die "$dir: $!";

while (defined(my $file = readdir DIR)) {
    next if($file =~ /^\.+$/);
    print "The directory and file are $dir/$file\n";
    open my $fh, '<', "$dir/$file" or die "$dir/$file: $!";
    $function{$file}->($fh, $dir) if exists $function{$file};
}
closedir DIR;



sub print_allergies{
    my ($fh, $dir)  = @_;

    print "\nprinting allergies from directory $dir\n";
    while (<$fh>){
        next if (/^#/);
        print  $_ ;
    }
}
[download]

update: added example of passing a variable other than a file handle.

Thanks! This is what I did not have correct.

$function{$file}->($fh, $dir)
...
allergies       => \&print_allergies
[download]

Thanks very much!