Summary of new syntax features in PHP7.0 and php7.1

This article brings you a summary of the new grammatical features in PHP7.0 and php7.1. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

New features of php7.0:

1, empty merge operator ( ??)

Simplified judgment

$param = $_GET['param'] ?? 1;

is equivalent to:

$param = isset($_GET['param']) ? $_GET['param'] : 1;

2. Two types of variable type declaration

Mode: mandatory (default) and strict mode
Types: string, int, float and bool

function add(int $a) { 
    return 1+$a; 
} 
var_dump(add(2);

3, return value type declaration

Function and anonymous function You can specify the type of the return value

function show(): array { 
    return [1,2,3,4]; 
}

function arraysSum(array ...$arrays): array {
return array_map(function(array $array): int {
return array_sum($array);
}, $arrays);
}

4. Spaceship operator (combined comparison operator)

The spaceship operator is used to compare two expressions. It returns -1, 0 or 1 when a is greater than, equal to or less than b respectively. The principle of comparison follows PHP's regular comparison rules.

// Integers
echo 1 <=> 1; // 0
echo 1 <=> 2; // -1
echo 2 <=> 1; // 1
// Floats
echo 1.5 <=> 1.5; // 0
echo 1.5 <=> 2.5; // -1
echo 2.5 <=> 1.5; // 1
// Strings
echo "a" <=> "a"; // 0
echo "a" <=> "b"; // -1
echo "b" <=> "a"; // 1

5. Anonymous classes

Now supports instantiating an anonymous class through new class, which can be used to replace some complete classes that are "burn after use" definition.

interface Logger {
    public function log(string $msg);
}

class Application {
    private $logger;

    public function getLogger(): Logger {
        return $this->logger;
    }

    public function setLogger(Logger $logger) {
        $this->logger = $logger;
    }
}

$app = new Application;
$app->setLogger(new class implements Logger {
    public function log(string $msg) {
        echo $msg;
    }
});
var_dump($app->getLogger());

6. Unicode codepoint translation syntax

This accepts a Unicode codepoint in hexadecimal form and prints out a UTF-8 surrounded by double quotes or heredoc Encoded format string. Any valid codepoint is accepted, and the leading 0 can be omitted.

 echo "\u{9876}"

Old version output: \u{9876}
New version input: Top

7, Closure::call()

Closure: :call() now has better performance and is a short and concise way to temporarily bind a method to a closure on an object and call it.

class Test {
    public $name = "lixuan";
}

//PHP7和PHP5.6都可以
$getNameFunc = function () {
    return $this->name;
};
$name = $getNameFunc->bindTo(new Test, 'Test');
echo $name();
//PHP7可以,PHP5.6报错
$getX = function () {
    return $this->name;
};
echo $getX->call(new Test);

8. Provide filtering for unserialize()

This feature is designed to provide a safer way to unpack unreliable data. It prevents potential code injection through whitelisting.

//将所有对象分为__PHP_Incomplete_Class对象
$data = unserialize($foo, ["allowed_classes" => false]);
//将所有对象分为__PHP_Incomplete_Class 对象 除了ClassName1和ClassName2
$data = unserialize($foo, ["allowed_classes" => ["ClassName1", "ClassName2"]);
//默认行为，和 unserialize($foo)相同
$data = unserialize($foo, ["allowed_classes" => true]);

9. IntlChar

The newly added IntlChar class is designed to expose more ICU functions. This class itself defines many static methods for operating unicode characters from multiple character sets. Intl is a Pecl extension. It needs to be compiled into PHP before use. You can also apt-get/yum/port install php5-intl

printf('%x', IntlChar::CODEPOINT_MAX);
echo IntlChar::charName('@');
var_dump(IntlChar::ispunct('!'));

The above routine will output:
10ffff
COMMERCIAL AT
bool(true)

10. Expectation

Expectation is to use backwards and enhance the previous assert() method. It makes enabling assertions cost-effective in production and provides the ability to throw specific exceptions when assertions fail. The older version of the API will continue to be maintained for compatibility purposes, and assert() is now a language construct that allows the first argument to be an expression, not just a string to be calculated or a boolean to be tested.

ini_set('assert.exception', 1);
class CustomError extends AssertionError {}
assert(false, new CustomError('Some error message'));

The above routine will output:
Fatal error: Uncaught CustomError: Some error message

11、Group use declarations

From the same Namespace imported classes, functions, and constants can now be imported all at once with a single use statement.

//PHP7之前
use some\namespace\ClassA;
use some\namespace\ClassB;
use some\namespace\ClassC as C;
use function some\namespace\fn_a;
use function some\namespace\fn_b;
use function some\namespace\fn_c;
use const some\namespace\ConstA;
use const some\namespace\ConstB;
use const some\namespace\ConstC;

// PHP7之后
use some\namespace\{ClassA, ClassB, ClassC as C};
use function some\namespace\{fn_a, fn_b, fn_c};
use const some\namespace\{ConstA, ConstB, ConstC};

12. intp()

Receives two parameters as dividend and divisor, and returns the integer part of their division result.

var_dump(intp(7, 2));

Output int(3)

13, CSPRNG

Add two new functions: random_bytes() and random_int(). Can be encrypted Produce protected integers and strings. In short, random numbers become safe.
random_bytes — A cryptographically protected pseudo-random string
random_int — A cryptographically protected pseudo-random integer

14, preg_replace_callback_array()

A new function preg_replace_callback_array() has been added. Using this function can make the code more elegant when using the preg_replace_callback() function. Before PHP7, the callback function would be called for every regular expression, and the callback function was contaminated on some branches.

15. Session options

Now, the session_start() function can receive an array as a parameter, which can override the session configuration items in php.ini.
For example, set cache_limiter to private and close the session immediately after reading it.

session_start(['cache_limiter' => 'private',
               'read_and_close' => true,
]);

16. Return value of generator

The concept of generator is introduced in PHP5.5. Each time the generator function is executed, it gets a value identified by yield. In PHP7, when the generator iteration is completed, the return value of the generator function can be obtained. Obtained through Generator::getReturn().

function generator() {
    yield 1;
    yield 2;
    yield 3;
    return "a";
}

$generatorClass = ("generator")();
foreach ($generatorClass as $val) {
    echo $val ." ";

}
echo $generatorClass->getReturn();

The output is: 1 2 3 a

17. Introduce other generators into the generator

You can introduce another or several generators into the generator A generator, just write yield from functionName1

function generator1() {
    yield 1;
    yield 2;
    yield from generator2();
    yield from generator3();
}

function generator2() {
    yield 3;
    yield 4;
}

function generator3() {
    yield 5;
    yield 6;
}

foreach (generator1() as $val) {
    echo $val, " ";
}

Output: 1 2 3 4 5 6

18. Define a constant array through define()

define('ANIMALS', ['dog', 'cat', 'bird']);
echo ANIMALS[1]; // outputs "cat"

New features of php7.1:

1. Nullable type

type NULL is now allowed. When this feature is enabled, the parameters passed in or the result returned by the function are either of the given type or null. You can make a type nullable by preceding it with a question mark.

function test(?string $name) {
    var_dump($name);
}

The above routine will output:

string(5) "tpunt"
NULL
Uncaught Error: Too few arguments to function test(), 0 passed in...

2、Void 函数

在PHP 7 中引入的其他返回值类型的基础上，一个新的返回值类型void被引入。 返回值声明为 void 类型的方法要么干脆省去 return 语句，要么使用一个空的 return 语句。 对于 void 函数来说，null 不是一个合法的返回值。

function swap(&$left, &$right) : void {
    if ($left === $right) {
        return;
    }
    $tmp = $left;
    $left = $right;
    $right = $tmp;
}
$a = 1;
$b = 2;
var_dump(swap($a, $b), $a, $b);

以上例程会输出：

null
int(2)
int(1)

试图去获取一个 void 方法的返回值会得到 null ，并且不会产生任何警告。这么做的原因是不想影响更高层次的方法。

3、短数组语法 Symmetric array destructuring

短数组语法（[]）现在可以用于将数组的值赋给一些变量（包括在foreach中）。 这种方式使从数组中提取值变得更为容易。

$data = [
    ['id' => 1, 'name' => 'Tom'],
    ['id' => 2, 'name' => 'Fred'],
];
while (['id' => $id, 'name' => $name] = $data) {
    // logic here with $id and $name
}

 4、类常量可见性

现在起支持设置类常量的可见性。

class ConstDemo
{
    const PUBLIC_CONST_A = 1;
    public const PUBLIC_CONST_B = 2;
    protected const PROTECTED_CONST = 3;
    private const PRIVATE_CONST = 4;
}

5、iterable 伪类

现在引入了一个新的被称为iterable的伪类 (与callable类似)。 这可以被用在参数或者返回值类型中，它代表接受数组或者实现了Traversable接口的对象。 至于子类，当用作参数时，子类可以收紧父类的iterable类型到array 或一个实现了Traversable的对象。对于返回值，子类可以拓宽父类的 array或对象返回值类型到iterable。

function iterator(iterable $iter) {
    foreach ($iter as $val) {
        //
    }
}

6、多异常捕获处理

一个catch语句块现在可以通过管道字符(|)来实现多个异常的捕获。 这对于需要同时处理来自不同类的不同异常时很有用。

try {
    // some code
} catch (FirstException | SecondException $e) {
    // handle first and second exceptions
} catch (\Exception $e) {
    // ...
}

7、list()现在支持键名

现在list()支持在它内部去指定键名。这意味着它可以将任意类型的数组 都赋值给一些变量（与短数组语法类似）

$data = [
    ['id' => 1, 'name' => 'Tom'],
    ['id' => 2, 'name' => 'Fred'],
];
while (list('id' => $id, 'name' => $name) = $data) {
    // logic here with $id and $name
}

8、支持为负的字符串偏移量

现在所有接偏移量的内置的基于字符串的函数都支持接受负数作为偏移量，包括数组解引用操作符([]).

var_dump("abcdef"[-2]);
var_dump(strpos("aabbcc", "b", -3));

以上例程会输出：

string (1) "e"
int(3)

9、ext/openssl 支持 AEAD

通过给openssl_encrypt()和openssl_decrypt() 添加额外参数，现在支持了AEAD (模式 GCM and CCM)。 
通过 Closure::fromCallable() 将callables转为闭包 
Closure新增了一个静态方法，用于将callable快速地 转为一个Closure 对象。

class Test {
    public function exposeFunction() {
        return Closure::fromCallable([$this, 'privateFunction']);
    }
    private function privateFunction($param) {
        var_dump($param);
    }
}
$privFunc = (new Test)->exposeFunction();
$privFunc('some value');

以上例程会输出：

string(10) "some value"

10、异步信号处理 Asynchronous signal handling

A new function called pcntl_async_signals() has been introduced to enable asynchronous signal handling without using ticks (which introduce a lot of overhead). 
增加了一个新函数 pcntl_async_signals()来处理异步信号，不需要再使用ticks(它会增加占用资源)

pcntl_async_signals(true); // turn on async signals
pcntl_signal(SIGHUP,  function($sig) {
    echo "SIGHUP\n";
});
posix_kill(posix_getpid(), SIGHUP);

以上例程会输出：

SIGHUP

11、HTTP/2 服务器推送支持 ext/curl

Support for server push has been added to the CURL extension (requires version 7.46 and above). This can be leveraged through the curl_multi_setopt() function with the new CURLMOPT_PUSHFUNCTION constant. The constants CURL_PUST_OK and CURL_PUSH_DENY have also been added so that the execution of the server push callback can either be approved or denied. 
翻译： 
对于服务器推送支持添加到curl扩展（需要7.46及以上版本）。 
可以通过用新的CURLMOPT_PUSHFUNCTION常量 让curl_multi_setopt()函数使用。 
也增加了常量CURL_PUST_OK和CURL_PUSH_DENY，可以批准或拒绝 服务器推送回调的执行

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