Yet another way (OO style):

package Foo;

sub one {
...
}
sub two {
...
}
sub AUTOLOAD {
  goto &one;
}


package main;
# Then in your main routine

Foo->$sub($data);
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Doing it this way you'd have to first make sure that $sub is not one of the UNIVERSAL::* methods (can, isa, ??? -- update: or define your own 'can' and 'isa' which just goes to 'one').