Came across this blog post on
today. Seems to me the author needs a fair amount of sleep and then a
cop of coffee or two ...
... it all started with me trying to be clever with array_map and
Being clever is not a good thing. In my experience it always leads to
crappy code that you'll regret ever having done when time comes round to
code maintenance. Whenever the thought strikes you - "I'll come up with
a clever solution for this" - think twice, then step back and redesign.
I knew array_filter existed and what it was all about since before,
however I started working with something requiring array_map first,
all well and OK, array_map looks like this: array_map(’callback’,
Array). So then I assumed I could use array_filter in the same
fashion, big mistake.
As Henrik goes on to point out, PHP is not consistent in function
definitions, which is a problem. A much bigger problem is that something
with 5 years of self-proclaimed PHP-hacking experience doesn't check
function definitions but wastes time assuming either that 1) function
definitions are the same for similar functions (which apparently he
knows is not the case) or that 2) he knows the functions already when he
doesn't. How many tools are there for checking PHP function definitions
easily? A simple search key in FireFox would have solved this in 30
So the class method containing both the array_map and array_filter
callbacks has only one argument: \$name, which contains a partial
string to match against users’ full names or usernames. I wanted to
use that variable inside the array_filter callback.
What was I thinking? I knew that it wouldn’t work, of course it
wouldn’t since callbacks are just an ugly hack bolted on top of PHP,
hell you’re calling the name of the callback in the form of a string.
I’ve got no idea how the interpreter is actually evaluating this stuff
and I don’t want to know, I’d rather keep what I have in my stomach
where it is.
Yes, callbacks are nasty but they provide for quite a lot of
functionality. You can use the name of a function, an object method, the
result of create_function or even (from PHP 5.3) a PHP closure. But of
course, that doesn't directly solve Henriks problem: passing that extra
variable to array_filter or array_map. And here there obviously is a
problem that could use a nice and simple design like allowing for
passing an extra variable. Workarounds are possible, though:
public function getFriendsByPartial($partial)
$this->_partial = $partial;
return array_filter($input_array, array($this, 'callback'));
public function callback($input)
// test $input against $this->_partial here
Is that pretty? No. Does it work? Pretty sure it does. Does it keep
things inside the class? Yup. Did it take me longer to write than it
took me to read Henriks post? No.
However, this was apparently not clean enough, so instead of doing
something simple like this, the alternative was writing up a function
using foreach and stripos. Only Henrik couldn't remember (after 5 years)
that there's strpos and stripos (and, again, checking function lists was
not an option) so he wasted more time.
I probably lost over an hour just on that one and it’s happened to me
at least 5 times, yes roughly one time per year, just this fucking
shitty little function. Why oh why are there two of them? You have to
be rainman to navigate this swamp, of course I should’ve used
stripos()! What an idiot I am right? Why couldn’t my pea brain
remember that, especially since it’s happened to me so many times
before? I must truly be a complete moron.
I don't think he's a moron for not remembering the difference between
strpos and stripos (or rather that both exist). If there's anything at
play here, it's the belief that you can actually remember all the
functions of PHP. So when the ironic morale comes
When it comes to PHP, don’t try to be clever, and most importantly of
all, know your functions, all 5000 of them.
it's very hard not to just shrug it off and think that the programmers
arrogance got to Henrik. Don't ever think you can know all of the
functions in PHP - look them up before you start abusing, that way
you'll avoid spending more than 5 minutes on the thing that cost Henrik
I'm glad that in the end though, he did gain the insight of not trying
to be clever.