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

...
...time passes...

$encoded_output = &$sub_ref;

sub template {
    my $e = shift;
    my $common = sub {...shared stuff...}
    if ($e eq 'b') { return sub {&$common; ...stuff...} }
    if ($e eq 'u') { return sub {&$common: ...other stuff...} }
etc.