Extracting information back out of a DBH

[Simon Wistow]

I'm dealing with some code that currently uses a lookup table for dbh 
handles with the hash key being based on the dsn, username and password 
passed in. 

I'm adapting it to be able to take in a random DB handle and therefore 
I'd really like to be able to extract the dsn and username back out 
again. Preferably I'd like to be able to get the password out again to 
but I can't think of a database whereby a user can use multiple 
passwords with the resulting handles having different abilities 
(although maybe I'm wrong).

DBH has a clone method which "duplicates the $dbh connection by 
connecting with the same parameters ($dsn, $user, $password) as 
originally used." 

which sounds like it should mean that the information is available but 
since it also does something with a closure it's possible that for .xs 
based drivers something more funky is going on.

So basically, I have 3 questions:

1) Is there any reason not just to use the username and dsn in the hash
2) Is there any way to get that information out of a dbh
3) Is there another way to do this?

I suppose, I could either force the user to pass in a username and dsn 
when they pass in the dbh or, alternatively, just use a random hash and 
lose the auto pooling of handles.

Simon