I had a job intereview today for a PHP Application Developer position. Naturally I was nervous. But I think I did a good job. Except for one question:
“Define ‘Variable Variables’ as it relates to PHP.”
My brain froze. It’s like, the words made sense… but not really. My response was a confused look, followed by “I don’t believe I’ve heard that term in reference to PHP.”
The guy nodded, gave a half smile and moved on.
I left the interview, shook hands all around, and walked out. I hit the button for the elevator, got in, and pressed lobby. And then I did this:
For at that moment, I suddenly realized what Variable Variables were. And worst yet… I’ve used many variable variables!
Just for good Karma:
“Variable Variables” allow you to assign the name of one variable as a string in another variable, and then access the named variable. For example:
1: $salutation = 'Hello, World!';
2: $a = 'salutation';
3: echo ${$a};
{$a} says “take the contents of the string $a and put them here as the variable name,” which turns line 3 into:
1: echo $salutation;
Which causes the script to print “Hello, World.” I could explain Magic Functions, but completely blanked on Variable Variables.
I also forgot that the @ sign is used to change the error reporting level, rendering errors “suppressed,” but it’s usually a Bad Thing™ for efficiency (Excellent explanation here. But I threw up the “It’s used for function decorators in Python!” in hopes of at least showing SOME programmer savvy (and instead mostly looking like a random dork).
I hope this post can save somebody else the humiliation of forgetting about Variable Variables… or this may just become your reaction:
