The aspects of PHP that are bad (and there are more than a few) are easily tooled around. We have a review-time tool that parses your PHP, symbolically executes it, and looks for dubious idioms, flagging them for you and your reviewer.
Meanwhile, PHP gets a number of things very right. For instance:
* State: there is none across requests. Oh sure, there's APC, and the filesystem, and databases, etc., but those are all accessed via libraries. There is no PHP-level state that survives a request, which provides natural fault isolation: a request which goes wrong doesn't take the server down with it, or live on to corrupt other requests.
* Concurrency: PHP's concurrency model is the web request. If you want to run some code in parallel, curl to localhost. If you wrap an appropriate library around this, it looks just like Erlang's actors. This is shared-nothing concurrency, which turns out to be a compelling local maximum.
* Interactivity: The development workflow PHP provides is very productive. You save and load the page. You don't save, optionally recompile, restart the server, wait for it to initialize, forget what's different from the last three times you tried this because this has all taken three minutes and you forgot to write it down, etc.
These three things turn out to be among the most important parts of a server-side language, and PHP gets them very, very right. The rightness was accidental, not by design, but this doesn't make it any less right.
Also, the language itself can be improved. In the HipHop toolchain, -v Eval.EnableHipHopSyntax=true turns on a bunch of (backwards-compatible) features we've added to our PHP dialect, the most notable of which are XHP (syntax for using XML literals as PHP expressions) and generators (inspired by Python's, using similar 'yield' syntax). I put up some sample code for a talk just the other day, if you're curious: https://github.com/kmafb/hiphop-samples
>These three things turn out to be among the most important parts of a server-side language
So the language does two of these three things by not doing them at all ?
State: oh there's no state across requests.
Concurrency: No shared resources, no threads, but we'll call it shared-nothing concurrency and then say it looks like Erlang!! Amazing. An Erlang actor holds mutable state and sends immutable messages. A web request in PHP does neither.
> PHP gets them very, very right. The rightness was accidental.
Completely agree. Here you have a language that decides to tackle hard problems in CS by not tackling them. Then it becomes uber-pervasive because you can do "hello world" over the web by just doing <?print("hello world");?> Once the traction is a given, we argue about why not tackling hard problems is actually "very, very right".
Nobody's asking you to like PHP. I'm explaining why it's effective; if you'd like to build something better, there are affirmative lessons to learn from PHP's undeniable successes. While your point about Erlang is correct for pure PHP, one of the nice things about the "curl as concurrency model" world is that the thing on the other end of the curl doesn't have to be PHP, or stateless.
Getting "hard problems" right by realizing they're intractable and refusing to solve them is a perfectly valid system design choice, even though it drives people up a wall when they first encounter it. For an example that has stood the test of time, check out UNIX's handling of the "PC-losering" problem: http://dreamsongs.com/WIB.html. When modern systems people read about this controversy, it seems kind of insane; of course system calls can be interrupted, and of course you don't want the OS to be magically trying to make them look transactional by backing up and restarting your system call when the world is really in an unknown and unknowable state. Ctl-C on a read() shouldn't restart the read(), unless the application thinks it should, and only the app really knows. EINTR was the non-solution that acknowledged the intractability of solution.
Historically, UNIX is a "worse-is-better" system not unlike PHP. I claim anyone designing a new system from scratch to replace it should learn from it, though, both mistakes and successes. PHP is not free of successes.
The point is that it's still shared state, so it's possible in practice to take down your server if you manage to corrupt your database or a file on your filesystem.
About the only thing you're protected against is memory leaks, and that seems to be because you have to, otherwise PHP would fall over in a big heap: https://www.google.com/search?q=php+memory+leak
I haven't had any problems with memory leaks running things like Django or Bottle.
Meanwhile, PHP gets a number of things very right. For instance:
* State: there is none across requests. Oh sure, there's APC, and the filesystem, and databases, etc., but those are all accessed via libraries. There is no PHP-level state that survives a request, which provides natural fault isolation: a request which goes wrong doesn't take the server down with it, or live on to corrupt other requests.
* Concurrency: PHP's concurrency model is the web request. If you want to run some code in parallel, curl to localhost. If you wrap an appropriate library around this, it looks just like Erlang's actors. This is shared-nothing concurrency, which turns out to be a compelling local maximum.
* Interactivity: The development workflow PHP provides is very productive. You save and load the page. You don't save, optionally recompile, restart the server, wait for it to initialize, forget what's different from the last three times you tried this because this has all taken three minutes and you forgot to write it down, etc.
These three things turn out to be among the most important parts of a server-side language, and PHP gets them very, very right. The rightness was accidental, not by design, but this doesn't make it any less right.
Also, the language itself can be improved. In the HipHop toolchain, -v Eval.EnableHipHopSyntax=true turns on a bunch of (backwards-compatible) features we've added to our PHP dialect, the most notable of which are XHP (syntax for using XML literals as PHP expressions) and generators (inspired by Python's, using similar 'yield' syntax). I put up some sample code for a talk just the other day, if you're curious: https://github.com/kmafb/hiphop-samples