$encode = 'u'; # example, could be 'p', 'b', or 'u'
$sub_ref = template($encode);

sub template {
    my $e = shift;
    if ($e eq 'b') { return sub {...stuff...} }
    elsif ($e eq 'u') { return sub {...other stuff...} }
    else { return sub {...yet more...} }
}

...time passes...

$encoded_output = &$sub_ref;