This is a clarifying FAQ for the idea presented on internals@. It attempts to address many points that were raised repeatedly in the discussion that ensued.
Trying to shorten the lengthy email into a couple of points:
This is not related to short tags, and the short tags deprecation RFC was not the main motivator for this idea. The goal of this proposal is a lot more ambitious - it's to provide a clear vision for PHP - and to hopefully finally put to rest the tension between the two schools of thought on internals@ - by providing both of them with what they want.
This is not a fork. The codebase will be identical, it would be versioned together and developed by the same people. The binaries will be identical - if you'd install PHP, you'd be installing P++ and vice versa. The same binary will be running your PHP, P++ or combined PHP/P++ apps.
While it's not yet clear how one would 'mark' a file as a P++ file, it would probably be some sort of a special header at the top of the file, such as:
<?p++?> <?php 'Hello, world!'; ?>
In addition, we may find ways to mark entire namespaces as P++, so that frameworks don't have to explicitly mark every individual file as P++.
Thankfully, it doesn't mean that at all. The vast majority of code will be shared between the PHP mode and the P++ mode - both in source and at runtime.
Data structures, key subsystems, extensions, web server interfaces, OPcache - and mostly everything else - will be be the exact same code running regardless of whether the file being executed is a PHP one or a P++ one. The only additional development overhead will be the specific areas of difference between PHP and P++.
It's true that it means we'd have to maintain two versions of certain pieces of code, and that we'll have some if() statements in various places - as P++ is likely to have additional checks compared to PHP. However, these are elements that would have to be introduced anyway if we're ever to move towards a stricter version of PHP. Moreover, since even folks in the strict crowd don't suggest that we move towards a stricter future without providing a migration path - effectively, the efforts involved with this approach and virtually any other approach are similar.
There are many issues with this approach. Even if we disregard the fact that this leaves the huge dynamic-preferring crowd hanging with no feature or performance updates - it's impractical from a development effort point of view. Unlike this proposal - this does, in fact, mean a de-facto fork.
Yes and no. As mentioned above, when you install one - you'd have the other - so as far as apps go - you'd be able to run both dialects on a single server. However, practically speaking, projects and individuals are likely to typically pick and standardize on one or the other - similarly to how things went down with strict_types.
Yes. While we need to work out the exact mechanics, the designation of whether code is PHP or P++ will be at the file level - not at the request level. A single execution (request) may load many different files, and these files could be from both dialects. Code from PHP files will behave with the PHP semantics - while code from P++ files will behave with P++ semantics. Here too - this would be similar to strict_types.
While this may sound awkward at first - there could be very practical use cases for this. For instance - a P++ only framework that is being used by a PHP application - or vice versa. For those of you familiar with C and C++ - this is somewhat similar.
No, it just means it'll evolve differently. Strictness and type related features are likely to go just to P++, and only be available in P++ files. Bias for BC will remain in PHP (which won't mean it would never be broken - just that there'd have to be good return-on-investment cases for each such case). However - unrelated features - such as performance improvements in the engine (e.g. JIT), development in extensions, or new async-related features - will be available for both PHP and P++.
There are numerous benefits to this approach. First, it gives both camps on internals@ - and beyond - a good solution to their aspirations. Those who prefer the dynamic nature of PHP get to keep it, while those who prefer a more strictly typed language - get to obtain it without being bound by any limitations of PHP. The alternative to that is a zero sum game - where the win of one group is the loss of the other, and vice versa.
Beyond being a good technological solution - that enables us to support our entire audience in the least amount of effort - this could also bring an end to key source of contention on internals@ in recent years.
Finally - although most of the readers of this document are likely to be technology people - it should be noted that launching P++ that would start with a clean slate - could have substantial positioning/branding advantages. Companies, development managers and individual developers who have ruled out PHP - are more likely to take note of a P++ launch, than of a launch of PHP 8.0 or PHP 9.0.
To a degree, we are. But this isn't a flaw of this idea - but a representation of reality as it already exists on the ground.
As mentioned above, there's a huge crowd out there that likes the dynamic nature of PHP, and looks warily at the attempts to make it more and more type-oriented.
At the same time - there's another huge crowd out there that looks at PHP and thinks to themselves “why is it evolving so slowly towards finally getting rid of this dynamic nonsense?”
There's no right or wrong here. Both points of view are valid. When we look at potential solutions to bridge between these two contradictory points of views, there aren't too many of them available:
There's no shortage of challenges before we can run our first P++ app.