this week
This week started off with going over the solution to Reverse, where we combined the random access and bidirectional versions into one function that picks the right approach at compile time. I thought it was pretty cool that the same function could be faster on a vector while still working on a list.
We then went through the different ways to loop in C++ and the containers in the standard library, comparing each one to its Java equivalent along with the cost of their operations. The part that stood out to me was how easy it is to accidentally loop over copies instead of references, which means your changes silently don’t stick. It also tied back nicely to last week’s iterator categories, since some algorithms just won’t compile on certain containers because they don’t provide the right kind of iterator.
The concept that finally clicked for me was friend functions. I never really understood why you’d make an operator a non-member function, but seeing that s == "abc" works while "abc" == s doesn’t when it’s a member function made it make sense. We also compared nested classes in C++ to Java, which was a nice refresher.
Unfortunately, I didn’t do too well on Exercise #4, where we had to write a Range class with its own iterator. Putting together everything from the week in a limited amount of time was harder than I expected, and it showed me that understanding the concepts in lecture isn’t the same as being able to write them out quickly. I’m planning to go back over the solution and rewrite it on my own before the test next week.
Project #2: Voting was also due this week, and it was satisfying to finally get all the ballot redistribution working.
As for the paper, the Open-Closed Principle says that software should be open for extension but closed for modification, so you can add new behavior without changing code that already works. It connected well with what we’ve been doing with iterators, since the standard algorithms work with any container that provides the right iterators without ever needing to be changed themselves.