Even better, there's a standard module for this: Memoize.pm, if the function approach is good enough.

Example:

    use Memoize;
    BEGIN {
        *dbh = memoize(sub () {
            DBI::->connect(...)
        })
    }

    dbh()->foo; # connect and do foo.
    dbh()->bar; # use cached object and do bar.
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The BEGIN block isn't necessary, but it'll make the prototype work.

I can't test it, but I don't see why it shouldn't work.

Update: If you really want a variable you may want to check out Tie::Memoize which also is a standard module I think. It uses hashes.

ihb