my %Templates = (
   header=>q{
      #### HEADER ####
      # yadda yadda yadda
      ################
   },
   config=>q{
      #### CONFIG ####
      # Sets the frobnitz
      #DEFINE FROBNITZ=Blevin
      ################
   },
   . . .
);

sub get_template {
   my $tpl_name = shift;
   die "Template '$tpl_name' doesn't exist!"
      unless exists $Templates{$tpl_name};
   return $Templates{$tpl_name};
}

# Now you can use it like:

print get_template('header');