What are the new features of PHP7? Compilation of common new features of php7

In PHP7, due to the modification of most of the code of the underlying engine and the improvement of PHP performance through various methods, some new syntax has also been added to PHP7. The use of these syntaxes can also help improve performance. Let's sort out the new features commonly used in php7.

1. ?? Operator (NULL merge operator)

I put this first because I think it is very useful. Usage:

$a = $_GET['a'] ?? 1;

It is equivalent to:

<?php
$a = isset($_GET[&#39;a&#39;]) ? $_GET[&#39;a&#39;] : 1;

We know that the ternary operator can be used like this:

$a ?: 1

But this is based on $a already defined On the premise. The new ?? operator can simplify judgment.

2. Function return value type declaration

Examples provided by official documents (note that the side length parameter syntax of ... is in PHP 5.6 or above Only available in version):

<?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]));

From this example, we can see that now functions (including anonymous functions) can specify the type of return value.

The way this statement is written is somewhat similar to swift:

func sayHello(personName: String) -> String {
    let greeting = "Hello, " + personName + "!"
    return greeting
}

This feature can help us avoid some problems caused by PHP's implicit type conversion. Thinking about the expected results before defining a function can avoid unnecessary mistakes.

But there is also a feature that needs attention here. PHP 7 adds a declare directive: strict_types, which uses strict mode.

When using return value type declaration, if it is not declared in strict mode, and if the return value is not the expected type, PHP will still perform cast type conversion on it. But if it is strict mode, a Fatal error of TypeError will be issued.

Forced mode:

<?php
function foo($a) : int
{
    return $a;
}

foo(1.0);

The above code can be executed normally, and the foo function returns int 1 without any errors.

Strict mode:

<?php
declare(strict_types=1);

function foo($a) : int
{
    return $a;
}

foo(1.0);
# PHP Fatal error:  Uncaught TypeError: Return value of foo() must be of the type integer, float returned in test.php:6

After the declaration, a fatal error will be triggered.

Is it similar to the strict mode of js?

3. Scalar type declaration

The formal parameter type declaration of a function in PHP 7 can now be a scalar. In PHP 5, it can only be a class name, interface, array or callable (PHP 5.4, that is, it can be a function, including anonymous functions). Now you can also use string, int, float and bool are gone.

Official example:

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

var_dump(sumOfInts(2, '3', 4.1));

It should be noted that the strict mode problem mentioned above also applies here: in forced mode (default, both forced type conversion), there will still be errors that do not conform to the The expected parameters are cast to type, and a TypeError fatal error is triggered in strict mode.

4. Use batch declaration

In PHP 7, use can declare multiple classes or functions or const in one sentence:

<?php
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};

But You still have to write out the name of each class or function or const (there is no from some import * method like python).

The question you need to pay attention to is: if you are using a framework based on composer and PSR-4, can this writing method successfully load class files? In fact, it is possible. The autoloading method registered by composer searches the location according to the namespace of the class when the class is called. This way of writing has no effect on it.

In addition to the above new features, let me briefly mention a few:

PHP 5.3 started to have anonymous functions, and now there are anonymous classes;

define can now be defined Constant array;

Closure (Closure) adds a call method;

The generator (or iterator is more appropriately called) can have a final return value (return), or it can pass yield New syntax for from into another generator (generator delegate).

The two new features of generators (return and yield from) can be combined. You can test the specific appearance by yourself. PHP 7 is now at RC5 and the final version should be coming soon.

Recommended related articles:

PHP7 New Features Introduction

A brief talk about the major new features of php7, a brief talk about php7

[Translation]Introduction to PHP7: New and Removed Features

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