Question

This question came to my mind because I was working on a project, and I created the following method:

private void GoToFirstPage() {
    CurrentPage = 0;
}

which I use in a few methods related to pagination.

Is it a good idea? Or should I be calling CurrentPage = 0; instead in all the method calls?

Answer 1

First, how likely is it that you’d ever change the implementation of GoToFirstPage? For example, if this is, say, a PDF viewer, might the next version have a continuous scrolling mode as well as a page-by-page mode, so you’ll keep a CurrentTopLine instead of a CurrentPage? In that case, if you’ve got CurrentPage = 0; in 15 different places, and you have to change all 15 of them to if (PageMode) CurrentPage = 0; else CurrentTopLine = 0;, that’s a perfect opportunity for stupid bugs to creep into your code because you forgot about 1 of them and only changed 14. If you’ve got it in a method, you only need to change things in one place.

In some cases, having a name for the method gives you some extra documentation (and unlike a comment, it won’t get stale as things change, because you have to keep it up to date or things won’t compile). In this case, I don’t think that’s relevant, because CurrentPage = 0; is just as readable and meaningful as GoToFirstPage();, but in many cases, it is.

Occasionally, performance is a concern. Function calls aren’t free, after all. But in this case, it’s hard to imagine it could ever matter. It’s not like you’re going to call GoToFirstPage millions of times in a tight loop, right?

So, if none of these are relevant, how do you decide? The most important factor is probably what’s more idiomatic for your language, codebase, etc. In a typical Java program, a function like GoToFirstPage(); would fit in perfectly, and it might even be implemented as SetCurrentPage(0); for another layer of encapsulation. In a typical Python program, the current_page property would be part of even the public API of the class. Neither one is necessarily bad or good, and consistency of style is important in keeping your code readable.