Best practices using multiple object instances?

[eluser]tarsusc81[/eluser]
I'm somewhat familiar with Datamapper. I'm leery, as another developer I know who's used it ran into exactly what I would expect: Page loads bogged down by THOUSANDS of queries where only a few would have sufficed. (That's in complex scenarios. I'm sure it's fine when dealing with a one or a few records.)

But that's neither here nor there. I used a model as an example, but I'm talking about any circumstance where functionality with multiple object instances is needed, not just objects that correspond with database entities. (For another example, how about writing HTML form functionality using a technique that represents a form as an object?)

Your example works, but that's the kind of code I was wondering if I could avoid. CodeIgniter makes that kind of manual checking/including unnecessary for it's conventional structures, so I'm exploring whether there's a way to avoid it for this too.