$b = [$a, $a = $b];
Works on PHP 5.4 and up.
I know this is not very practical, for daily work, but it can come handy in a job interview.
♦ ♦ ♦
[Update:June 16, 2016]
In PHP 7.1.x it will finally be possible to use a cleaner swap short-code:
[$a, $b] = [$b, $a];
Lately I encountered several opportunities to try and install the ODBTP
library, at first I was working on new systems, so when i encountered errors when simply doing pecl install odbtp I tried installing from source, encountering errors during the make command I came to my senses and managed just fine using the basic MSSQL library in PHP.
Then a few weeks ago I needed to upgrade an existing system relying on ODBTP with tight coupling, so i had no choice but to find a way to overcome the errors.
After research on the Internet I came to solution but had no time to document the final solution, until today when I installed a test zone on a separate system and remembered only vaguely what I was looking for.
Follow the instructions here
except for this: After moving the php/ext content, patch the php_odbtp.c file using the attached file.
This patch was checked on Gentoo linux, Ubuntu server 12.04.1 and Linux mint 14, the variable as far that I could gather from the complaints is the PHP version.