in reply to OOP: How to construct multiple instances of a class at once
When dealing with situations like this, I like to make my objects “lazy.” They don’t actually fetch information unless and until they have to. One strategy is to send the constructor a hashref of known-good data that you might have obtained from the current row in your query; certain keys are obligatory. The (trusting...) object initializes itself partially with them ... suspiciously checking the values, and using the “setters” if such things exist so that all necessary side-effects take place. But it knows that it hasn't done all of the fetching that it might conceivably need to do ... and, if the need to do so never arises, it never will. “Lazy.” Therefore, efficient.
Your “list of users” is, initially, just a list of blessed-hashes. But they are all smart enough to know when, and if, and what, additional information must be obtained or manipulated to do everything that they are designed by you to do.