Elf Sternberg

The code declares two new references to existing data without an apparent improvement in readability, accessibility or clarity.

Using aliases for the purposes of documentation is a fairly standard practice.

In the code snippet provided, presumably hlf is an alias for the center of the sprite, indicating that we are using half it's width and height to position the sprite. I could certainly take issue with the use of variable names here. It might be that the person who wrote the code struggled to figure out what cx/cy where, and when they did, they chose to document that in the code. It's not the best job I've seen at doing that, but that is certainly a standard idiom that used commonly in programming. In fact, I'll be happy to admit that I used the hlf identifier as a hint when trying and figure out what the code was doing. As an identifier, hlf carries more semantic information than cx/cy.

I will admit, I have, on occasion, created my own version of object, either so I can extend it with additional methods, or reformat the data so that it make more sense internal to the application I'm developing.

In this case, the object was not extended, but rather narrowed, something which is a not unreasonable thing to do.