Like every developer, I’ve got a particular configuration for most sites I deploy. My WordPress sites are mostly all based on my Pilau parent/child themes, and I’ve a set of “usual suspect” plugins I include in most projects. Some plugins—in particular Developer’s Custom Fields—are pretty much indispensable to my work. So much so, that for a while I assumed, in my custom theme code, that the plugin would be installed.
More recently I’ve forced myself to follow best practices better. So, even if I know a certain plugin will be installed and active, because I manage the site, I still surround a call to a function from that plugin with a
function_exists() test. I just found out why that’s a good idea.