What's the best Perl practice for returning hashes from functions?

Question

I am mulling over a best practice for passing hash references for return data to/from functions.

On the one hand, it seems intuitive to pass only input values to a fun

Answer 1

Uh... "passing hashes can only be done by reference"?

sub foo(%) {
    my %hash = @_;
    do_stuff_with(%hash);
}

my %hash = (a => 1, b => 2);
foo(%hash);

What am I missing?

I would say that if the issue is that you need to have multiple outputs from a function, it's better as a general practice to output a data structure, probably a hash, that holds everything you need to send out rather than taking modifiable references as arguments.