The document discusses major concerns and changes involved in migrating to PHP 7, including error handling modifications, deprecated behaviors, and incompatibilities with PHP 5. Key updates include changes to exception handling, the behavior of functions like list(), and the removal of previously existing features and functions. The author emphasizes the importance of reviewing migration documentation to address these updates effectively.

1. Migrating to PHP 7
John Coggeshall – International PHP Conference, 2016
Berlin, Germany
@coogle, john@coggeshall.org

2. Who’s This Guy?
• The Author of ext/tidy
• (primary) Author in (almost) 5 books on PHP going from PHP 4 to
PHP 7
• Speaking at conferences for a long time
!!!!!
circa 2004 today

3. Major Concerns when Migrating to PHP 7
• Error Handling
• Variable Handling
• Control Structure Changes
• Removed Features / Changed Functions
• Newly Deprecated Behaviors
• This talk will not cover every single detail of the changes in PHP 7.
That’s what Migration Documentation is for:
http://php.net/manual/de/migration70.php

4. Error Handling
• One of the biggest breaks you may have to deal with migrating to
PHP 7 will be error handling
• Especially when using Custom Error Handlers
• Many fatal / recoverable errors from PHP 5 have been converted
to exceptions
• Major Break: The callback for set_exception_handler() is not
guaranteed to receive Exception objects

5. Fixing Exception Handlers
<?php
function my_handler(Exception $e)
{
/* ... */
}
<?php
function my_handler(Throwable $e)
{
/* ... */
}
PHP 5 PHP 7

6. Other Internal Exceptions
• Some internal class constructors in PHP 5 would create objects in
unusable states rather than throw exceptions
• In PHP 7 all class constructors throw exceptions
• Notably this was a problem in some of the Reflection Classes
You should always be prepared to handle an exception thrown from
PHP 7 internal classes in the event something goes wrong

7. Parser Errors
• In PHP 5, parsing errors (for instance, from an include_once
statement) would cause a fatal error
• In PHP 7 parser errors throw the new ParseError exception
Again, your custom error handlers and exception handlers may need
updating to reflect this new behavior

8. E_STRICT is Dead
Situation New Behavior
Indexing by a Resource E_NOTICE
Abstract Static Methods No Error
”Redefining” a constructor No Error
Signature mismatch during inheritance E_WARNING
Same (compatible) property used in two
traits
No Error
Accessing a static property non-statically E_NOTICE
Only variables should be assigned by
reference
E_NOTICE
Only variables should be passed by reference E_NOTICE
Calling non-static methods statically E_DEPRECATED

9. Indirect Variables, Properties, Methods
• In PHP 5 complex indirect access to variables, properties, etc. was
not consistently handled.
• PHP 7 addresses these inconsistencies, at the cost of backward
compatibility
Typically most well-written code will not be affected by this.
However, if you have complicated indirect accesses you may hit
this.

10. Indirect Variables, Properties, Methods
Expression PHP 5 PHP 7
$$foo[‘bar’][‘baz’] ${$foo[‘bar’][‘baz’]} ($$foo)[‘bar’][‘baz’]
$foo->$bar[‘baz’] $foo->{$bar[‘baz’]} ($foo->$bar)[‘baz’]
$foo->$bar[‘baz’]() $foo->{$bar[‘baz’]}() ($foo->$bar)[‘baz’]()
Foo::bar[‘baz’]() Foo::{$bar[‘baz’]}() (Foo::$bar)[‘baz’]()
If you are using any of the expression patterns on the left
column the code will need to be updated to the middle
“PHP 5” column to be interpreted correctly.

11. list() Mayhem
• There is a lot of code out there that takes the assignment order of
the list() statement for granted:
<?php
list($x[], $x[]) = [1, 2];
// $x = [2, 1] in PHP 5
// $x = [1, 2] in PHP 7
• This was never a good idea and you should not rely on the order in
this fashion.

12. list() Mayhem
• Creative use of the list() statement with empty assignments will
also now break
<?php
// Both will now break in PHP 7
list() = $array;
list(,$x) = $array;

13. list() Mayhem
• Finally, list() can no longer be used to unpack strings.
<?php
list($a, $b, $c) = “abc”;
// $a = “a” in PHP 5, breaks in PHP 7

14. Subtle foreach() changes – Array Pointers
• In PHP 5 iterating over an array using foreach() would cause the
internal array pointer to move for each iteration
<?php
$a = [1, 2]
foreach($a as &$val) {
var_dump(current($a));
}
// Output in PHP 5:
// int(1)
// int(2)
// bool(false)
<?php
$a = [1, 2]
foreach($a as &$val) {
var_dump(current($a));
}
// Output in PHP 7:
// int(1)
// int(1)
// int(1)

15. Subtle foreach() changes – References
This subtle change may break code that modifies arrays by
reference during an iteration of it
<?php
$a = [0];
foreach($a as &$val) {
var_dump($val);
$a[1] = 1;
}
// Output in PHP 5
// int(0)
<?php
$a = [0];
foreach($a as &$val) {
var_dump($val);
$a[1] = 1;
}
// Output in PHP 7
// int(0)
// int(1)
In PHP 5 you couldn’t add to an array, even when passing it by
reference and iterate over them in the same block

16. Integer handler changes
• Invalid Octal literals now throw parser errors instead of being
silently ignored
• Bitwise shifts of integers by negative numbers now throws an
ArithmeticError
• Bitwise shifts that are out of range will now always be int(0)
rather than being architecture-dependent

17. Division By Zero
• In PHP 5 Division by Zero would always cause an E_WARNING and
evaluate to int(0), including attempting to do a modulus (%) by
zero
• In PHP 7
• X / 0 == float(INF)
• 0 / 0 == float(NaN)
• Attempting to do a modulus of zero now causes a
DivisionByZeroError exception to be thrown

18. Hexadecimals and Strings
• In PHP 5 strings that evaluated to hexadecimal values could be
cast to numeric values
• I.e. (int)“0x123” == 291
• In PHP 7 strings are no longer directly interpretable as numeric
values
• I.e. (int)”0x123” == 0
• If you need to convert a string hexadecimal value to its integer
equivalent you can use filter_var() with the FILTER_VALIDATE_INT
and FILTER_FLAG_ALLOW_HEX options to convert it to an integer
value.

19. Calls from Incompatible Contexts
• Static calls made to a non-static method with an incompatible
context (i.e. calling a non-static method statically in a completely
unrelated class) has thrown a E_DEPRECATED error since 5.6
• I.e. Class A calls a non-static method in Class B statically
• In PHP 5, $this would still be defined pointing to class A
• In PHP 7, $this is no longer defined

20. yield is now right associative
• In PHP 5 the yield construct no longer requires parentheses and
has been changed to a right associative operator
<?php // PHP 5
echo yield -1; // (yield) – 1;
yield $foo or die // yield ($foo or die)
<?php // PHP 7
echo yield -1; // yield (-1)
yield $foo or die // (yield $foo) or die;

21. Misc Incompatibilities
• There are a number of other (smaller) incompatibilities between
PHP 5 and PHP 7 worth mentioning
• ASP-style tags <% %> have been removed
• <script language=“php”> style tags have been removed
• Assigning the result of the new statement by reference is now fatal error
• Functions that have multiple parameters with the same name is now a
compile error
• switch statements with multiple default blocks is now a compile error
• $HTTP_RAW_POST_DATA has been removed in favor of php://input
• # comments in .ini files parsed by PHP are no longer supported (use
semicolon)
• Custom session handlers that return false result in fatal errors now

22. Removed Functions
• Numerous functions have been removed in PHP 7 and replaced
with better equivalents where appropriate
Variable Functions
call_user_method()
call_user_method_array()
Mcrypt
mcrypt_generic_end()
mcrypt_ecb()
mcrypt_cbc()
mcrypt_cfb()
mcrypt_ofb()
Intl
datefmt_set_timezone_id()
IntlDateFormatter::setTimeZoneId()
System
set_magic_quotes_runtime()
magic_quotes_runtime()
set_socket_blocking()
dl() (in PHP-FPM)
=
GD
imagepsbbox()
imagepsencodefont()
imagepsextendfont()
imagepsfreefont()
imagepsloadfont()
imagepsslantfont()
imagepstext()
• Removed Extensions: ereg, mssql, mysql, sybase_ct

23. Removed Server APIs (SAPIs) and extensions
• Numerous Server APIs (SAPIs) have been removed from PHP 7:
• aolserver
• apache
• apache_hooks
• apache2filter
• caudium
• continunity
• isapi
• milter
• nsapi
• phttpd
• pi3web
• roxen
• thttpd
• tux
• webjames

24. Deprecated Features
• A number of things have been deprecated in PHP 7, which means
they will now throw E_DEPRECATED errors if you happen to be
using them in your code
• PHP 4 style constructors
• Static calls to non-static methods
• Passing your own salt to the password_hash() function
• capture_session_meta SSL context option
• For now these errors can be suppressed (using the @ operator) but
the code should be updated as necessary.

25. Changes to Core Functions
• When migrating from PHP 5 to PHP 7 there are a few functions
that have changed behaviors worth noting
• mktime() and gmmktime() no longer accept the $is_dst parameter
• preg_replace() no longer supports the /e modifier and
preg_replace_callback() must now be used
• setlocale() no longer accepts strings for the $category parameter. The
LC_* constants must be used
• substr() now returns an empty string if then $string parameter is as
long as the $start parameter value.

26. Name Conflicts
• There are a lot of new things in PHP 7 that didn’t exist in PHP 5
• New Functions
• New Methods
• New Classes
• New Constants
• New Exceptions
• You should review the PHP Migration documentation for what’s
been added to determine if any code you’ve written now conflicts
with something internal to PHP 7
• For example, do you have an IntlChar class in your application?

27. Thank you!
John Coggeshall
john@coggeshall.org, @coolge