I think the original blog post is badly worded. We can see by the proposed refactor that in fact those 10 lines were not identical - they were only similar. The

I think the original blog post is badly worded. We can see by the proposed refactor that in fact those 10 lines were not identical - they were only similar. The formulas for resizing the top-left corner of a rectangle are different from the formulas for modifying the bottom-right of an oval. They look quite similar, but one will have a + instead of a minus here and another one there etc. The complexity is built into geometry itself in this case, and "abstracting" it away is only moving the mess around, it fundamentally can't (perhaps there is some clever mathematical abstraction that could using some special number group, but unless you have that built-in, it'll probably be much harder to implement the special arithmetic using built-in ints than you gain).