Avoiding cleverness at all costs. Simple code that is easy to both read and write without strong efforts to follow senseless DYI or take on abstraction for the sake of abstraction.
Can anyone give a specific example of code they've worked with that was "too clever"? Based on my experience, if a coworker wanted to "avoid cleverness" I imagine we'd end up arguing over something like a for-loop versus a map, but such small code decision matter very very little in comparison to overall architecture, and where you place the "seams" in your system. So I ask, when you have felt that code is "too cleve…
One I deal with at work is someone trying to be "clever" and coming up with some annotation based tool to automatically serialize and deserialize objects to a third party system. It's got complex class heirarchies, interception points, etc and I regularly have to crawl through this code. The "not clever" way would be a function that translates the objects to the very simple csv format. In fact I've done that to test interacting with it and when the bash version is simpler to read than the c# version you know it's over complicated.
Another frequent one is "this code is repeated, better move it to a function", problem is you then need to make a change and you have to go through every code path to check it's relevency or add optional parameters, then next time it needs to change you have to check all code paths and inspect which ones are using which paramters. The "not clever" way is to leave the repetitive code, this can have it's own downsides like fixing one place and missing another, but those are much easier to deal with.
Basically use the least level of abstraction that can reasonably get the job done. Your php example probably could have used a little more abstraction like functions and structures but most "enterprisy" code I see could use a lot less.