The best new features introduced in the new PHP 7.4.

1. Top ten of php 7.4
Andrea Giannantonio
Team Leader in Immobiliare.it
@JellyBellyDev

2. RELEASE DATE PHP 7.4
•Alpha1 - 13 Jun 2019
•Beta1 - 25 Jul 2019
•RC1 - 5 Sep 2019
•RC2 - 19 Sep 2019
•RC3 - 03 Oct 2019
•RC4 - 18 Oct 2019
•RC5 - 31 Oct 2019
•RC6 - 14 Nov 2019
•7.4.0 - 28 Nov 2019 (GA)
•7.4.1 - 18 Dec 2019 (GA)
•7.4.2 - 23 Jan 2020 (GA)

3. TOP TEN
•Typed Properties
•Arrow Functions
•Null Coalescing Assignment Operator
•Spread Operator in Array
•Foreign Function Interface
•Weak References
•Covariant Returns and Contravariant Parameters
•Preloading
•Deprecate left-associative ternary operator
•Performance of PHP 7.4

4. ONE
Typed Properties

5. PARAM AND RETURN TYPES: PHP 7.1

6. Allowed: bool, int, float, string, array, object,
iterable, self, parent, any class or interface
name, and nullable types (?type)
Not Allowed: void and callable
TYPED PROPERTIES: PHP 7.4

7. TYPED PROPERTIES: NULL

8. TYPED PROPERTIES: STRICT_TYPES OFF

9. TYPED PROPERTIES: INVARIANT
Property types (public and protected) are invariant

10. TWO
Arrow Functions

11. ARROW FUNCTIONS

12. ARROW FUNCTIONS

13. ARROW FUNCTIONS
Syntax: fn(parameter_list) => expr
Note: fn is a reserved word in PHP 7.4

14. THREE
Spread Operator in Array

15. SPREAD OPERATOR
Note that this only works with arrays with numerical keys.

16. SPREAD OPERATOR
It also works on Traversable objects

17. FOUR
Null Coalescing Assignment Operator

18. NULL COALESCING ASSIGNMENT OPERATOR
Note that, while the coalesce operator `??` is a comparison operator, `??=` is an assignment operator.

19. FIVE
Foreign Function Interface

20. FOREIGN FUNCTION INTERFACE
•Enables the execution of C code directly from PHP
•Provides a FFI class to manage the bridge between C and PHP
•A C function can be executed as a PHP method of FFI class
•php.ini: `ffi.enable=false`

21. FFI: EXAMPLE 1

22. FFI: EXAMPLE 2

23. FFI: PHP TENSORFLOW
Dmitry Stogov has developed an experimental binding
of TensorFlow library in PHP using FFI:
dstogov/php-tensorflow

24. SIX
Weak References

25. WEAK REFERENCES
Weak References allow the programmer to retain a reference to an object which does not prevent the
object from being destroyed; They are useful for implementing cache like structures.

26. SEVEN
Covariant Returns and Contravariant
Parameters

27. COVARIANT RETURNS AND CONTRAVARIANT PARAMETERS
Variance is a property of class hierarchies describing how the types of a type constructor
affect subtypes.
•Invariant: if the type of the super-type constrain the type of the subtype.
•Covariant: if the ordering of types is preserved (types are ordered from
more specific to more generic).
•Contravariant: if it reverses the order (types are ordered from more
generic to more specific).
Currently, PHP has mostly invariant parameter and return types, with few exceptions. This
RFC proposes to allow covariance and contravariance on parameter types and return types.
In general, a type constructor can be:

28. COVARIANT RETURN TYPE: EXAMPLE

29. CONTRAVARIANT PARAMETER TYPE: EXAMPLE

30. EIGHT
Preloading

31. OPCACHE

32. PRELOADING
"On server startup – before any application code is run – we may load a
certain set of PHP files into memory – and make their contents
“permanently available” to all subsequent requests that will be served by
that server. All the functions and classes defined in these files will be
available to requests out of the box, exactly like internal entities."
Dmitry Stogov

33. PRELOADING
• Preloading is controlled by a specific php.ini directive: opcache.preload
• This directive specifies a PHP script to be compiled and executed at server start-up
• Each file to cache, should be added in this script using opcache_compile_file()

34. PRELOADING: COMPOSITION
opcache.preload=“/tmp/preload.php”
OPCache Preloading in Symfony
opcache.preload=/path/to/project/var/cache/prod/App_KernelProdContainer.preload.php

35. PRELOADING: BENCHMARKS
• Preloading disabled
• Naive preloading - all Laravel and application code
I found this benchmark by stitcher.io on Laravel project
• Preloading Optimised - dumped all classes used by `get_declared_classes()`
Scenarios:

36. PRELOADING: BENCHMARKS
Requests per second Time per request
That's around a 25% performance gain compared to not using
preloading, and an 8% gain compared to using the naive approach.

37. PRELOADING: CONS
• Restart the web server to update opcache.preload
• Not compatible with host running multiple applications, or multiple
versions of applications

38. NINE
Deprecate left-associative ternary operator

39. DEPRECATE LEFT-ASSOCIATIVE TERNARY OPERATOR
Unlike most other languages, the ternary operator in PHP is left-associative rather than right-associative.
Not only being uncommon, it is also confusing for programmers who switch between different languages.
PHP 7.4 proposes to remove the left-associativity and requires the use of parentheses instead.
• Starting from PHP 7.4, nested ternaries without explicit use of parentheses will throw a deprecation warning.
• Starting from PHP 8.0, there will be a compile runtime error.

40. TEN
Performance of PHP 7.4

41. PERFORMANCE OF PHP 7.4
• He compared the execution time of PHP7.4RC1 with PHP 7.1, 7.2 and 7.3
• He used Zendbench.php script as benchmark
I found this benchmark on PHP 7.X by Enrico Zimuel
• He took the total execution time
• Full experiment report here

42. PERFORMANCE OF PHP 7.4: RESULTS
PHP ver. Exec. time (in sec)
7.1.32 455
7.2.22 437
7.3.9 373
7.4RC1 334

43. PERFORMANCE OF PHP 7.4: RESULTS
PHP 7.4 IS THE FASTEST!
• 7.4RC1 is 26% faster than 7.1.32
• 7.4RC1 is 22% faster than 7.2.22
• 7.4RC1 is 10% faster than 7.3.9

44. LET’S GO CODING IN PHP 7.4

45. Thanks for the attention
Andrea Giannantonio
@JellyBellyDev

46. REFERENCES
• https://www.php.net
• https://wiki.php.net/rfc#php_74
• https://www.zimuel.it/slides/pugtorino/php74#/
• https://www.zimuel.it/blog/benchmarking_PHP74
• https://medium.com/@daniel.dan/whats-new-in-php-7-4-top-10-features-that-you-need-to-know-e0acc3191f0a
• https://kinsta.com/blog/php-7-4/
• https://stitcher.io/blog/new-in-php-74
• https://stitcher.io/blog/php-preload-benchmarks
• https://support.cloud.engineyard.com/hc/en-us/articles/205411888-PHP-Performance-I-Everything-You-Need-to-
Know-About-OpCode-Caches
• https://carbon.now.sh/