The document discusses changes introduced in PHP 7 regarding scalar type hints and return types, emphasizing their optional nature and how they enhance type safety. Examples illustrate the difference between PHP 5 and PHP 7 type hinting, showing the implementation of strict typing. It also highlights the advantages of clearer function input/output definitions leading to more robust code.

1. PHP7: Scalar Type
Hints & Return Types
2015 April 1
Kansas City PHP User Group

2. PHP 7
It’s coming!
Q4 2015
Image by Aaron Van Noy
https://plus.google.com/+AaronVanNoy/posts/HPtSxAGcpAd

3. PHP 5 Type Hinting
PHP 5.1
• Objects
• Interfaces
• Array
PHP 5.4
• Callable

4. PHP5 Type Hinting Example
<?php
/**
* Type Hinting in PHP 5 is only for classes,
* interfaces, & callable
*
* @param DateTime $timestamp
* @return string
*/
function getDayOfWeek(DateTime $timestamp)
{
return $timestamp->format('l');
}
$times = [];
$times[] = new DateTime('now');
$times[] = new DateTimeImmutable('+3 days');
foreach($times as $time) {
printf("Today is %sn",
getDayOfWeek($time));
}

5. PHP5 Type Hinting Example
<?php
/**
* Type Hinting in PHP 5 is only for classes,
* interfaces, & callable
*
* @param DateTime $timestamp
* @return string
*/
function getDayOfWeek(DateTime $timestamp)
{
return $timestamp->format('l');
}
$times = [];
$times[] = new DateTime('now');
$times[] = new DateTimeImmutable('+3 days');
foreach($times as $time) {
printf("Today is %sn",
getDayOfWeek($time));
}
Today is Thursday
Fatal error: Argument 1 passed to
getDayOfWeek() must be an instance of
DateTime, instance of DateTimeImmutable
given, called in /vagrant_data/
php5TypeHint.php on line 19 and defined in /
vagrant_data/php5TypeHint.php on line 9

6. PHP5 Type Hinting Example
<?php
/**
* Type Hinting in PHP 5 is only for classes,
* interfaces, & callable
*
* @param DateTimeInterface $timestamp
* @return string
*/
function getDayOfWeek(DateTimeInterface
$timestamp)
{
return $timestamp->format('l');
}
$times = [];
$times[] = new DateTime('now');
$times[] = new DateTimeImmutable('+3 days');
foreach($times as $time) {
printf("Today is %sn",
getDayOfWeek($time));
}

7. PHP5 Type Hinting Example
<?php
/**
* Type Hinting in PHP 5 is only for classes,
* interfaces, & callable
*
* @param DateTimeInterface $timestamp
* @return string
*/
function getDayOfWeek(DateTimeInterface
$timestamp)
{
return $timestamp->format('l');
}
$times = [];
$times[] = new DateTime('now');
$times[] = new DateTimeImmutable('+3 days');
foreach($times as $time) {
printf("Today is %sn",
getDayOfWeek($time));
}
Today is Thursday
Today is Sunday

8. PHP 7 Scalar Type Hinting
PHP 5 Type Hinting +++ Scalars
• Strings
• Integers
• Floats
• Booleans

9. Scalar Type Hinting
• Not turned on by default
• Turn on by making `declare(strict_types=1);` the
first statement in your file
• Only strict on the file with the function call

10. PHP7 Scalar Type Hinting
Example 1: Turned Off
<?php
declare(strict_types=0);
/**
* @param int $number
* @param string $street
* @param string $apt
* @return string
*/
function createStreetAddress(int $number,
string $street, string $apt = null)
{
if ($apt) {
return sprintf('%d %s, #%s', $number,
$street, $apt);
} else {
return sprintf('%d %s', $number,
$street);
}
}
echo createStreetAddress(221, "Baker St",
"B") . PHP_EOL;
echo createStreetAddress("221", "Baker St",
"B") . PHP_EOL;

11. PHP7 Scalar Type Hinting
Example 1: Turned Off
<?php
declare(strict_types=0);
/**
* @param int $number
* @param string $street
* @param string $apt
* @return string
*/
function createStreetAddress(int $number,
string $street, string $apt = null)
{
if ($apt) {
return sprintf('%d %s, #%s', $number,
$street, $apt);
} else {
return sprintf('%d %s', $number,
$street);
}
}
echo createStreetAddress(221, "Baker St",
"B") . PHP_EOL;
echo createStreetAddress("221", "Baker St",
"B") . PHP_EOL;
221 Baker St, #B
221 Baker St, #B

12. PHP7 Scalar Type Hinting
Example 1: Turned On
<?php
declare(strict_types=1);
/**
* @param int $number
* @param string $street
* @param string $apt
* @return string
*/
function createStreetAddress(int $number,
string $street, string $apt = null)
{
if ($apt) {
return sprintf('%d %s, #%s', $number,
$street, $apt);
} else {
return sprintf('%d %s', $number,
$street);
}
}
echo createStreetAddress(221, "Baker St",
"B") . PHP_EOL;
echo createStreetAddress("221", "Baker St",
"B") . PHP_EOL;

13. PHP7 Scalar Type Hinting
Example 1: Turned On
<?php
declare(strict_types=1);
/**
* @param int $number
* @param string $street
* @param string $apt
* @return string
*/
function createStreetAddress(int $number,
string $street, string $apt = null)
{
if ($apt) {
return sprintf('%d %s, #%s', $number,
$street, $apt);
} else {
return sprintf('%d %s', $number,
$street);
}
}
echo createStreetAddress(221, "Baker St",
"B") . PHP_EOL;
echo createStreetAddress("221", "Baker St",
"B") . PHP_EOL;
221 Baker St, #B
Fatal error: Argument 1 passed to
createStreetAddress() must be of the type
integer, string given, called in /
vagrant_data/php7TypeHint.php on line 20 and
defined in /vagrant_data/php7TypeHint.php on
line 10

14. Introducing… return types
• Completely optional
• Declare strict same as for Scalar Type Hinting
• Only strict on the file with the function
declaration
• Tells the compiler that we expect to get
something of type Foo out of the function call

15. PHP 7 Return Types
Example 1: DateTime
<?php
declare(strict_types=1);
/**
* @return DateTime
*/
function getCurrentTime() : DateTime {
return new DateTime('now');
}
echo getCurrentTime()->format('l') . PHP_EOL;

16. PHP 7 Return Types
Example 1: DateTime
<?php
declare(strict_types=1);
/**
* @return DateTime
*/
function getCurrentTime() : DateTime {
return new DateTime('now');
}
echo getCurrentTime()->format('l') . PHP_EOL;
Thursday

17. PHP 7 Return Types
Example 1: Calculator
<?php
declare(strict_types=1);
/**
* @param int $num
* @param int $denom
* @return int
*/
function divide(int $num, int $denom) : int {
if (0 === $denom) {
return 9999999999;
} else {
return $num / $denom;
}
}
echo divide(7, 3) . PHP_EOL;

18. PHP 7 Return Types
Example 1: Calculator
<?php
declare(strict_types=1);
/**
* @param int $num
* @param int $denom
* @return int
*/
function divide(int $num, int $denom) : int {
if (0 === $denom) {
return 9999999999;
} else {
return $num / $denom;
}
}
echo divide(7, 3) . PHP_EOL;
Fatal error: Return value of divide() must be
of the type integer, float returned in /
vagrant_data/php7ReturnType.php on line 13 in
/vagrant_data/php7ReturnType.php on line 13

19. PHP 7 Return Types
Example 1: Calculator
<?php
declare(strict_types=1);
/**
* @param int $num
* @param int $denom
* @return float
*/
function divide(int $num, int $denom) : float
{
if (0 === $denom) {
return 9999999999;
} else {
return $num / $denom;
}
}
echo divide(7, 3) . PHP_EOL;

20. PHP 7 Return Types
Example 1: Calculator
<?php
declare(strict_types=1);
/**
* @param int $num
* @param int $denom
* @return float
*/
function divide(int $num, int $denom) : float
{
if (0 === $denom) {
return 9999999999;
} else {
return $num / $denom;
}
}
echo divide(7, 3) . PHP_EOL;
2.3333333333333

21. Great. PHP Just Got Hard.
Again.
• No. These are optional
• Weak Typing is still the default
• Strict typing forces the programmer to think more
clearly about a function’s input/output
• Think: “Filter input; escape output.”
• Leads the way to compiling PHP to Opcode
• Compiler can catch certain bugs before a user will

22. More Information
• Scalar Type Hinting & Return Types - RFC:
https://wiki.php.net/rfc/scalar_type_hints_v5
• Anthony Ferrara’s blog post about this:
http://blog.ircmaxell.com/2015/02/scalar-types-
and-php.html
• Building & Testing PHP 7:
http://akrabat.com/building-and-testing-php7/

23. Thank You
Eric Poe
eric@ericpoe.com
@eric_poe
Please rate this talk:
https://joind.in/14348