Re: Re: Reference to a sub return / Config::General

[Oberon]

> Don't worry about size unless you have to, and it sounds like you really don't.

I know, I know: don't microoptimize. But it's the principle dammit! <s>

No, I shan't worry about it. But I thought maybe there was some way around it that would teach me something new. <he said wistfully ...>

[revdiablo]

But I thought maybe there was some way around it

If the subroutine returns a list instead of a hashref, there's not much you can do about it.

Just for a little bit more explanation: when you say return %hash, the hash gets flattened into a plain ol' list. When you subsequently say my %hash = foo(), that shoehorns the list into a new hash. Again, there's nothing you can do about this without modifying the subroutine's return statement.

[Oberon]

> when you say return %hash, the hash gets flattened into a plain ol' list. When you subsequently say my %hash = foo(), that shoehorns the list into a new hash.

Ah, I hadn't thought of it that way. So I'm not only running into the difference between a value and a variable, but also the difference between a list and an array.

Although, come to think of it, those are basically analogous ...

[revdiablo]

So I'm not only running into the difference between a value and a variable, but also the difference between a list and an array.

Right. The only way you can really return an array itself (or, as previously discussed, a hash) is with a reference. Just like with return %hash, when you write return @array, the array is flattened. The elements are sucked out and put into a list. The list is returned. The caller can then grab that list and do what it wants with it; be it iterate through it, suck it into a new array, or even suck it into a hash.

It may seem complex at first, but really it's very simple. Your data structures get dismantled unless you use references.

Before you dismay at what happens to multi-level datastructures, keep in mind that these are only achievable in Perl via the use of references. They're perfectly safe, so things like @array = ([qw/one two/], [qw/three four/]); return @array will not blow up into tiny pieces. 8^)