However you do it, the function that does the conversion is going to have to know about the names of the default arguments. You may be able to shorten it a bit by making fix_args a regular function (instead of a method) and not using named parameters for it:

  my $arg = fix_args([qw(-name -age -mood)],\@_);
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but I can't think of a way to make it much less clumsy than that. On the other hand, your syntax doesn't really seem that clumsy to me...