in reply to Perl 5 OOP solutions
When someone makes claims that something is a "problem", particularly when they start waving the magic word "solution", it's sometimes insightful to replace "problem" with "possible issue" and then ask:
In the specific case the visibility of member variables (hash elements) of stock Perl objects, yes, they are visible. Is this a problem? It comes down to a matter of trust. If you trust yourself and your team to not abuse the feature, I'll argue, (based on experience with two substantial perl-based applications, one in the 600KLOC range) that visibility isn't an issue worth the cost of the various workarounds.
If you don't trust your team, then visibility is an issue, but isn't your biggest issue.