I think I'm just not explaining myself well.

Here's a rough example...

$result = $obj->functionA($obj->functionB());

I want whatever function B returns to be passed as a reference to function A. I don't know what function B is going to return because that whole line is generated by a Parse::RecDescent grammar which is writing the Perl script based on the parsing of a scripting language I designed.

If I knew functionB was always going to return a list, I could do...

$result = $obj->functionA([ $obj->functionB() ]);

Or if I knew it was going to be a hash...

$result = $obj->functionA({ $obj->functionB() });

I've thought of writing a function which takes in some values and returns a reference to them, whatever they might be...

$result = $obj->functionA($obj->createrightreftype($obj->functionB()));

But I can't think of any way to make createrightreftype do the right thing.

Does that make any more sense? I'm finding it difficult to describe this.

$result = $obj->functionA($obj->functionB());
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That's going to be calling method functionB in a list context. Therefore, the one and only answer you can have in Perl is "it is returning a list". Every other thing you think it might be doing is not happening.

Your statement of "always going to return a list" is therefore true. Your statement of "going to be a hash" is therefore always false.

I don't see the confusion here. It's the caller that decides what the called routine returns. It's that simple.

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

My thinking is that is functionB does...

return %myhash;

...then it's therefore returning a hash. In which case to pass a reference to that to functionA it would have to be...

$obj->functionA({ $obj->functionB() });

But if functionB did...

return @myarray;

Then I'd have to do...

$obj->functionA([ $obj->functionB() ]);

And it functionB did return...

return $scalar or return \$ref

Then it would be...

$obj->functionA($obj->functionB());

My problem is that I don't know which one of those four possibilities functionB is going to do, and therefore don't know whether to wrap it in braces (for a hash ref) or square brackets (for an array ref) or nothing (for a scalar, or if it's already a reference).

You have got me thinking however that I should always be doing the square bracket array reference however, because functionA can always find a way to deal with that.