New Important Features in PHP 7

Php 7 gives some important features through which you can really love to use and apply those things to your project So, let’s explore with new features.

Spaceship operator

The spaceship operator is used for comparing two expressions. It returns -1, 0 or 1 when $a is respectively less than, equal to, or greater than $b.


<?php
// Integers
echo <=> 1// 0
echo <=> 2// -1
echo <=> 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
?>

Constant arrays using define()

Array constants can now be defined with define(). In PHP 5.6, they could only be defined with const.


<?php
define
(‘ANIMALS’, [
‘dog’,
‘cat’,
‘bird’
]);

echo ANIMALS[1]; // outputs “cat”
?>

Return type declarations

PHP 7 adds support for return type declarations. Similarly to argument type declarations, return type declarations specify the type of the value that will be returned from a function. The same types are available for return type declarations as are available for argument type declarations.


<?php

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

print_r(arraysSum([1,2,3], [4,5,6], [7,8,9]));

The above example will output:

Array
(
    [0] => 6
    [1] => 15
    [2] => 24
)

Group use declarations

Classes, functions and constants being imported from the same namespace can now be grouped together in a single use statement.


<?php
// Pre PHP 7 code
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;

// PHP 7+ code
use some\namespace\{ClassAClassBClassC as C};
use function 
some\namespace\{fn_afn_bfn_c};
use const 
some\namespace\{ConstAConstBConstC};
?>

list() can always unpack objects implementing ArrayAccess

Previously, list() was not guaranteed to operate correctly with objects implementing ArrayAccess. This has been fixed.

CSPRNG Functions

Two new functions have been added to generate cryptographically secure integers and strings in a cross platform way: random_bytes() and random_int().

preg_replace_callback_array()

The new preg_replace_callback_array() function enables code to be written more cleanly when using the preg_replace_callback() function. Prior to PHP 7, callbacks that needed to be executed per regular expression required the callback function to be polluted with lots of branching.

Now, callbacks can be registered to each regular expression using an associative array, where the key is a regular expression and the value is a callback.

Session options

session_start() now accepts an array of options that override the session configuration directives normally set in php.ini.

These options have also been expanded to support session.lazy_write, which is on by default and causes PHP to only overwrite any session file if the session data has changed, and read_and_close, which is an option that can only be passed to session_start() to indicate that the session data should be read and then the session should immediately be closed unchanged.

For example, to set session.cache_limiter to private and immediately close the session after reading it:


<?php
session_start
([
‘cache_limiter’ => ‘private’,
‘read_and_close’ => true,
]);
?>

Integer division with intdiv()

The new intdiv() function performs an integer division of its operands and returns it.


<?php
var_dump
(intdiv(103));
?>

The above example will output:

int(3)

Generator delegation

Generators can now delegate to another generator, Traversable object or array automatically, without needing to write boilerplate in the outermost generator by using the yield from construct.


<?php
function gen()
{
yield 1;
yield 2;
yield from gen2();
}

function gen2()
{
yield 3;
yield 4;
}

foreach (gen() as $val)
{
echo 
$valPHP_EOL;
}
?>

The above example will output:

1
2
3
4

Generator Return Expressions

This feature builds upon the generator functionality introduced into PHP 5.5. It enables for a return statement to be used within a generator to enable for a final expression to be returned (return by reference is not allowed). This value can be fetched using the new Generator::getReturn() method, which may only be used once the generator has finished yielding values.


<?php

$gen = (function() {
yield 1;
yield 2;

return 3;
})();

foreach ($gen as $val) {
echo 
$valPHP_EOL;
}

echo $gen->getReturn(), PHP_EOL;

The above example will output:

1
2
3

Expectations

TExpectations are a backwards compatible enhancement to the older assert() function. They allow for zero-cost assertions in production code, and provide the ability to throw custom exceptions when the assertion fails.

While the old API continues to be maintained for compatibility, assert() is now a language construct, allowing the first parameter to be an expression rather than just a string to be evaluated or a boolean value to be tested.


<?php
ini_set
(‘assert.exception’1);

class CustomError extends AssertionError {}

assert(false, new CustomError(‘Some error message’));
?>

The above example will output:

Fatal error: Uncaught CustomError: Some error message

The new IntlChar class seeks to expose additional ICU functionality. The class itself defines a number of static methods and constants that can be used to manipulate unicode characters.


<?php

printf(‘%x’IntlChar::CODEPOINT_MAX);
echo 
IntlChar::charName(‘@’);
var_dump(IntlChar::ispunct(‘!’));

The above example will output:

10ffff
COMMERCIAL AT
bool(true)

Filtered unserialize()

This feature seeks to provide better security when unserializing objects on untrusted data. It prevents possible code injections by enabling the developer to whitelist classes that can be unserialized.


<?php

// converts all objects into __PHP_Incomplete_Class object
$data unserialize($foo, [“allowed_classes” => false]);

// converts all objects into __PHP_Incomplete_Class object except those of MyClass and MyClass2
$data unserialize($foo, [“allowed_classes” => [“MyClass”“MyClass2”]]);

// default behaviour (same as omitting the second argument) that accepts all classes
$data unserialize($foo, [“allowed_classes” => true]);

Scalar type declarations

Scalar type declarations come in two flavours: coercive (default) and strict. The following types for parameters can now be enforced (either coercively or strictly): strings (string), integers (int), floating-point numbers (float), and booleans (bool). They augment the other types introduced in PHP 5: class names, interfaces, array and callable.

<?php
// Coercive mode
function sumOfInts(int $ints)
{
return
array_sum($ints);
}

var_dump(sumOfInts(2, ‘3’, 4.1));

The above example will output:

int(9)

Null coalescing operator

The null coalescing operator (??) has been added as syntactic sugar for the common case of needing to use a ternary in conjunction with isset(). It returns its first operand if it exists and is not NULL; otherwise it returns its second operand.


<?php
// Fetches the value of $_GET[‘user’] and returns ‘nobody’
// if it does not exist.
$username $_GET[‘user’] ?? ‘nobody’;
// This is equivalent to:
$username = isset($_GET[‘user’]) ? $_GET[‘user’] : ‘nobody’;

// Coalescing can be chained: this will return the first
// defined value out of $_GET[‘user’], $_POST[‘user’], and
// ‘nobody’.
$username $_GET[‘user’] ?? $_POST[‘user’] ?? ‘nobody’;
?>

Anonymous classes

Support for anonymous classes has been added via new class. These can be used in place of full class definitions for throwaway objects:


<?php
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());
?>

The above example will output:

object(class@anonymous)#2 (0) {
}

Closure::call()

Closure::call() is a more performant, shorthand way of temporarily binding an object scope to a closure and invoking it.


<?php
class {private $x 1;}

// Pre PHP 7 code
$getX = function() {return $this->x;};
$getXCB $getX->bindTo(new A‘A’); // intermediate closure
echo $getXCB();

// PHP 7+ code
$getX = function() {return $this->x;};
echo 
$getX->call(new A);

The above example will output:

1
1
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