The slim AsynchHTTP.pm module gets and returns HTTP response header values through a hash reference, keyed by header name.  The SimpleAsynchHTTP.pm module propagates this behavior.  This is a problem because an HTTP response header can contain multiple instances of the Set-Cookie header.  Some applications (like the XMRadio plugin) need to get at each of the Set-Cookie headers to collect up multiple cookies, which is impossible with the hash.  As a result, I have needed to build alternate implementations for these modules.

I believe that this state of affairs may be the result of a long-standing error in the perl documentaiton for the base class Net::HTTP::NB -- the documentation asserts that the header return type is a hash, but in fact the base perl library code for this package is returning an array, which gets rolled into a hash as a run-time conversion.

It would be great if AsynchHTTP/SimpleAsynchHTTP interrogated the ref type of their caller's header data value, and returned the headers as an array if called with an array, or a hash if called with a hash.  This should be fully downward compatible with any code that is relying on a hash today.