PHP7 - Scalar Type Hints & Return Types

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

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

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

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)); 
}

<?php 
 
/** 
* 
* @param DateTime $timestamp 
* @return string 
*/ 
function getDayOfWeek(DateTime $timestamp) 
{ 
} 
 
$times = []; 
 
}
 
 
 
 
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

<?php 
 
/** 
* 
* @param DateTimeInterface $timestamp 
* @return string 
*/ 
function getDayOfWeek(DateTimeInterface
$timestamp) 
{ 
} 
 
$times = []; 
 
}

<?php 
 
/** 
* 
* @param DateTimeInterface $timestamp 
* @return string 
*/ 
function getDayOfWeek(DateTimeInterface
$timestamp) 
{ 
} 
 
$times = []; 
 
} 
Today is Thursday
Today is Sunday

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

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

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;

Example 1: Turned Off
<?php 
 
/** 
* @return string 
*/ 
{ 
if ($apt) { 
$street, $apt); 
} else { 
$street); 
} 
} 
 
"B") . PHP_EOL; 
"B") . PHP_EOL;
221 Baker St, #B
221 Baker St, #B

Example 1: Turned On
<?php 
 
/** 
* @return string 
*/ 
{ 
if ($apt) { 
$street, $apt); 
} else { 
$street); 
} 
} 
 
"B") . PHP_EOL; 
"B") . PHP_EOL;

Example 1: Turned On
<?php 
 
/** 
* @return string 
*/ 
{ 
if ($apt) { 
$street, $apt); 
} else { 
$street); 
} 
} 
 
"B") . PHP_EOL; 
"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

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

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

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

PHP 7 Return Types
Example 1: Calculator
<?php 
 
/** 
* @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;

PHP 7 Return Types
<?php 
 
/** 
* @return int 
*/ 
function divide(int $num, int $denom) : int { 
if (0 === $denom) { 
return 9999999999; 
} else { 
} 
} 
 
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

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

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

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

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/

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

PHP7 - Scalar Type Hints & Return Types

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