http://www.perlmonks.org?node_id=1002111


in reply to Re^2: Taint mode limitations
in thread Taint mode limitations

... [let] me tell it when I think I have looked at it closely enough (for example, [by] invoking a method untainted() on a variable) ...

But how would you "look at it" in the first place? Almost always by a regex match of some kind. So one would wind up with a statement like
    untaint($hinky) if my @safe = $hinky =~ m{ \A now (get) some (stuff) here \z }xms;
    then_do_safe_stuff_with($hinky, @safe);  # $hinky now safe, too

But what is to be gained by making explicitly required an action that is already implicit in the successful regex match? Everything still depends on crafting an effective validation regex.