PHP 5.6 – looking forward

Having taken a look in the past, now it’s time to look into the future, namely 5.6 (PHP 7 is the future future, we’ll get there eventually). So I’d like to make some predictions of what would work well and not so well and then see if it would make sense in two years or turn out completely wrong.

High impact

I expect those things to be really helpful for people going to PHP 5.6:

Constant expressions – the fact that you could not define const FOO = BAR + 1; was annoying for some for a long time. Now that this is allowed I expect people to start using it with gusto.

Variadics – while one can argue variadics are not strictly necessary, as PHP can already accept variable number of args for every function, if you’re going to 5.6 the added value would be enough so you’d probably end up using them instead of func_get_args and friends.

Operator overloading for extensions – the fact that you can sum GMP numbers with + is great, and I think more extensions like this would show up. E.g., for business apps dealing with money ability to work with fractions without precision loss is a must, and right now one has to invent elaborate wrappers to handle it. Having an extension for this would be very nice. Finding a way to transition from integer to GMP when number becomes too big would be a great thing too.
Still not convinced having it in userspace is a great idea, what C++ did to it is kind of scary.

phpdbg – not having gdb for PHP was for a long time one of the major annoyances. I expect to use it a lot.

Low impact

Function and constant importing – this was asked for a long time, but I still have hard time believing a lot of people would do it, since people who need imports usually are doing it in OO way anyway.

Hurdles

OpenSSL becoming strict with regard to peer verification by default may be a problem, especially for intranet apps running on self-signed certs. While this problem is easily fixable and the argument can be made that it should have been like this from the start – too many migrations go on very different paths depending on if it requires changing code/configs or not.

Adoption – again, with 5.5 adoption being still in single digits, I foresee a very slow adoption for 5.6. I don’t know a cure for “good enough” problem and I can understand people that do not want to move from something that already works, but look at the features! Look at the performance! I really hope people would move forward on this quicker.

While 5.4 will always have a special place in my heart, I hope people now staying on 5.2 and 5.3 would jump directly to 5.6 or at least 5.5. The BC delta in 5.5 and 5.6 is much smaller – I think 5.3->5.4 was the highest hurdle recently, and 5.4 to 5.5 or 5.6 should go much smoother.

Anything you like in PHP 5.6 and I forgot to mention? Anything that you foresee may be a problem for migration? Please add in comments. 

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Ruby-like iterators in PHP

I’ve started playing with Ruby recently, and one of the things that got my attention in Ruby were iterators. They are different inside from regular loops but work in a similar way, and looks like people (at least ones that write tutorials and code examples ūüėČ ) like to use them. For example, you can have:

arr = {"one" => 1, "two" => 2, "three" => 3}
arr.each do |key, val|
print "#{key}: is #{val}\n"
end

which iterates over a Ruby hash and prints:

three: is 3
two: is 2
one: is 1

So it got me thinking – suppose I wanted to do something like this in PHP (suppose I don’t like regular loop-y iterators for some weird reason). Naturally, I wouldn’t get it in the same concise form as Ruby does, since I can’t change the syntax. But I could get the essence. Let’s try it. First, the main iterator:

class RubyIterator {
  protected $_body;

  public function __construct($body) {
    if(!is_callable($body)) {
      throw new Exception("Iterator body should be a callable");
    }
    $this->_body = $body;
  }
  public function yield()
  {
    $args = func_get_args();
    call_user_func_array($this->_body, $args);
  }
}

Next, less try to make some class that uses it:

class RubyArray {
    protected $_arr;
    public function __construct(array $a)
    {
        $this->_arr = $a;
    }

    public function each($body) {
        $iter = new RubyIterator($body);
        foreach($this->_arr as $k => $v) {
            $iter->yield($k, $v);
        }
    }
}

and then:

/*
arr = {"one" => 1, "two" => 2, "three" => 3}
arr.each do |key, val|
    print "#{key}: is #{val}\n"
end
*/
    
$arr = new RubyArray(array("one" => 1, "two" => 2, "three" => 3));
$arr->each(function($key, $val) { echo "$key: is $val\n"; });

and the result the same, of course. Or, let’s try with ranges:

class RubyRange {
    protected $_from$_to;
    public function __construct($from$to) {
        $this->_from $from;
        $this->_to $to;
    }
    public function each($body) {
        $iter = new RubyIterator($body);
        for($i=$this->_from$i<=$this->_to$i++) {
            $iter->yield($i);
        }
    }
    
}

and use it:

/*
r = 1..10;
r.each do |i|
    print "#{i*i}\n"
end
*/

$rr = new RubyRange(110);
$rr->each(function($i) { echo $i*$i."\n"; });

which indeed produces:

1
4
9
16
25
36
49
64
81
100

And so on – if one wanted, whole set of iterator methods could be implemented (I’m of course too lazy to do that ūüôā ). I wonder if there are use cases that we can’t do there.

syntax I miss in PHP

Here are some syntax additions I’d like to see in PHP:

1. a()()
When a() returns a callable object (such as a closure) the second set of brackets would call it. That would allow to write some neat code. I am working on a patch for that but it’s a bit harder than I thought.

2. a()[$x]
This is kind of obvious, I wonder why don’t we have it? Should also be able to be an lvalue, though unless a() returns by-ref or return value is an object it may not do what one wanted.

3. foo(1,2,,4)
Syntax to skip a parameter in a call, which then will be substituted with the default as defined by the function. Would come handy if you have function with many defaults, and you only want to change the last one but leave the rest alone – now you don’t have to look up the actual default’s values.

4. foo(“a” => 1, “c” => 2, “d” => 4)
Named parameters call, which allows you to specify parameters in arbitrary order by name. Would allow to build nice APIs which could accept wider ranges of parameters without resorting to using arrays. That’d also imply call_user_func_array() would accept named arguments.
The problem here might be what to do with unknown arguments – i.e. ones that the function did not expect. I guess the function could just ignore them.

5. $a = [“a”, “b” => “c”];
I’d really like to have short array syntax. Yes, I know it was rejected so many times already, but I still like it.