Tackling the Beast: How to Gradually Upgrade a Legacy Code Base to PHP 7

Ann Gaffigan Intermediate

Hypothetically speaking, what if you wanted to change all of the lightbulbs in your house to use LED bulbs, but your current wiring didn’t support LED bulbs? You would need to re-wire your house, which would take a long time. In the meantime, you wouldn’t have any working electricity. Is there a better way? What if there was an adapter that could transition LED to work with old wiring if necessary, or if the wiring was new, just work as usual? That’s a metaphor for how I figured out how to gradually upgrade a legacy (LAMP) code base to be compliant with PHP 7.0. Since PHP deprecated the MySQL extension functions as of PHP 5.5.0 and removed in 7.0, we needed to transition a LOT of code in a legacy system to use the modern MySQLi extension functions. In trying to figure out how to upgrade the code base without ceasing new development on the system, we decided to use an adapter database class to allow us to transition gradually. In this session, we'll explain how the adapter class works and also the rules we put in place to ensure there was an end to the transition tunnel.