When it comes to introducing custom functionality into a WordPress project, the debate between functions.php vs. plugin usage is nothing new.
Generally speaking, I think of themes are presentation and plugins as functionality that transcend whatever theme or themes with which they’re installed.
But sometimes, this delineation isn’t so clear. For example, let’s say that you’re working on a theme that needs to introduce a custom meta box – or several – into the post editor screen.
Though this is presentation related in that it will impact what’s displayed to the users, it’s also a bit of custom functionality but it’s only relegated to this particular theme.
What then?