PHP 7 at a Glance

PHP7 is on it’s way! This is the largest shift in the PHP landscape since the upgrade to PHP 5.3. Most of us survived that and I’m sure we will survive this one as well.

To help you see the forrest for the trees, I’ve put together a list of all the RFCs that are marked as “Implemented” on the PHP wiki. Some of them have not yet been updated to “Implemented” status and there are still others in the “Pending Implementation” section.

The sections, “Classification”, “BC Break”, and “Impact” are subjective.

Backwards Compatibility (BC) Break

A lot of the RFCs to not break BC at all. The rest of them are labeled “Possible”. This is because there are no RFCs in this list that are guaranteed to break your code. Most of them labeled “Possible” will affect edge-cases but not the main body of your code.

I asked one Framework Architect recently how they were instructing their users on converting their code to PHP 7 and their answer was this.

“Migrating to php 7: Change your composer require to 7, and composer update. Done.”

So unlike the jump to PHP 5.3, this should be easy for most.

How can you tell if you code will be affected? Download a PHP 7 “Nightly Build” compile and try your code on it.

Impact

Impact was harder to guess. This is not the impact of the change on your code, it is the impact of the change on PHP developers in general. I tried to look at each RFC objectively and decide how much it would impact their style of coding or the execution of their code. Most of the changes, as you can see, are low, however, several of the Engine changes have a high impact. The PHPNG, and Exceptions in the Engine are two examples, the first won’t change how you code but it will impact the execution of your code. The second will change how you build applications.

The entire chart is presented for you below to digest. However, here are a few subsets of the data.

High Impact PHP 7 RFCs

• Move the phpng branch into master
• Catchable “call to a member function of a non-object”
• Null Coalesce Operator
• Return Type Declarations
• Scalar Type Declarations
• Abstract syntax tree
• Exceptions in the engine

Possible BC Breaks in PHP 7

• Continue output buffering despite aborted connection
• Replacing current json extension with jsond
• Make defining multiple default cases in a switch a syntax error
• Remove alternative PHP tags
• Abstract syntax tree
• Exceptions in the engine
• Reclassify E_STRICT notices
• Reserve More Types
• Uniform Variable Syntax
• ZPP Failure on Overflow
• Constructor behaviour of internal classes
• Fix “foreach” behavior
• Integer Semantics
• Removal of dead or not yet PHP7 ported SAPIs and extensions
• Fix list() behavior inconsistency
• Remove hex support in numeric strings
• Fix handling of custom session handler return values
• Remove PHP 4 Constructors

The Entire Chart

Further Reading

Want more information? Davey Shafik of Engine Yard has started a great article series, “What to expect when you are expecting: PHP 7″. The articles are short and concise and well worth a read.