Home > Article > Backend Development > Introducing new features from php7.3 to php7.4
1. Object attributes now support type declaration
<?php class User { public int $id; public string $name; } ?>
In the above example, $id will be forced to be converted to integer type, $name
is String type
Recommended (free):PHP7
2. Arrow function
Now the arrow function will Provide a short syntax for defining functions whose value declarations are unclear within the scope
<?php $factor = 10; $nums = array_map(fn($n) => $n * $factor, [1, 2, 3, 4]); // $nums = array(10, 20, 30, 40); ?>
3, limited return type covariance and parameter type covariance (Google Translate)
The following code will Will run
<?php class A {} class B extends A {} class Producer { public function method(): A {} } class ChildProducer extends Producer { public function method(): B {} } ?>
Full diff support is only provided when using autoloading. Within a single file, only non-cyclic type references can be used because all classes must be available before being referenced
4, Null merge assignment operator
<?php $array['key'] ??= computeDefault(); // is roughly equivalent to if (!isset($array['key'])) { $array['key'] = computeDefault(); } ?>
5, Unpacking inside arrays (Google The translation is to unpack inside the array. See if this is wrong, use English first)
<?php $parts = ['apple', 'pear']; $fruits = ['banana', 'orange', ...$parts, 'watermelon']; // ['banana', 'orange', 'apple', 'pear', 'watermelon']; ?>
6. Numeric character separator
Numeric characters can include underscores between numbers.
<?php 6.674_083e-11; // float 299_792_458; // decimal 0xCAFE_F00D; // hexadecimal 0b0101_1111; // binary ?>
7. Weak references
Weak references allow the programmer to retain a reference to an object that cannot be prevented from being destroyed does not prevent the object from being destroyed.)
8. Allow exceptions __toString()
can now be thrown through __toString()
Exceptions, which in previous versions would have resulted in a fatal error, existing string conversions that could have resulted in a fatal error have been converted to throw exceptions.
We will look at the rest of the expansion later
The above is the detailed content of Introducing new features from php7.3 to php7.4. For more information, please follow other related articles on the PHP Chinese website!