New features
Scalar type declarations
Scalar
type declarations
come in two flavours: coercive (default) and strict. The following types
for parameters can now be enforced (either coercively or strictly): strings
(string), integers (int), floating-point
numbers (float), and booleans (bool). They
augment the other types introduced in PHP 5: class names, interfaces,
array and callable.
To enable strict mode, a single declare directive must be placed at the
top of the file. This means that the strictness of typing for scalars is
configured on a per-file basis. This directive not only affects the type
declarations of parameters, but also a function's return type (see
return type declarations,
built-in PHP functions, and functions from loaded
extensions.
Full documentation and examples of scalar type declarations can be found in
the
type declaration
reference.
Return type declarations
PHP 7 adds support for
return type declarations.
Similarly to
argument type declarations,
return type declarations specify the type of the value that will be
returned from a function. The same
types
are available for return type declarations as are available for argument
type declarations.
Full documentation and examples of return type declarations can be found in
the
return type declarations.
reference.
Null coalescing operator
The null coalescing operator (??) has been added as
syntactic sugar for the common case of needing to use a ternary in
conjunction with isset(). It returns its first operand
if it exists and is not null; otherwise it returns its second operand.
Spaceship operator
The spaceship operator is used for comparing two expressions. It returns -1, 0
or 1 when $a is respectively less than, equal to, or greater
than $b. Comparisons are performed according to PHP's usual
type comparison rules.
Constant arrays using define()
Array constants can now be defined with
define(). In PHP 5.6, they could only be defined with
const.
Anonymous classes
Support for anonymous classes has been added via new
class. These can be used in place of full class definitions for
throwaway objects:
Full documentation can be found in the
anonymous class reference.
Unicode codepoint escape syntax
This takes a Unicode codepoint in hexadecimal form, and outputs that
codepoint in UTF-8 to a double-quoted string or a heredoc. Any valid
codepoint is accepted, with leading 0's being optional.
Closure::call() is a more performant, shorthand way
of temporarily binding an object scope to a closure and invoking it.
This feature seeks to provide better security when unserializing objects on
untrusted data. It prevents possible code injections by enabling the
developer to whitelist classes that can be unserialized.
The new IntlChar class seeks to expose additional
ICU functionality. The class itself defines a number of static methods and
constants that can be used to manipulate unicode characters.
In order to use this class, the Intl extension must be installed.
Expectations
Expectations are a
backwards compatible enhancement to the older assert()
function. They allow for zero-cost assertions in production code, and
provide the ability to throw custom exceptions when the assertion fails.
While the old API continues to be maintained for compatibility,
assert() is now a language construct, allowing the first
parameter to be an expression rather than just a string to be
evaluated or a bool value to be tested.
Full details on this feature, including how to configure it in both
development and production environments, can be found on the manual page
of the assert() language construct.
Group use declarations
Classes, functions and constants being imported from the same namespace
can now be grouped together in a single use statement.
Generator Return Expressions
This feature builds upon the generator functionality introduced into PHP 5.5.
It enables for a return statement to be used within a
generator to enable for a final expression to be returned (return by
reference is not allowed). This value can be fetched using the new
Generator::getReturn() method, which may only be used
once the generator has finished yielding values.
Being able to explicitly return a final value from a generator is a handy
ability to have. This is because it enables for a final value to be returned
by a generator (from perhaps some form of coroutine computation) that can be
specifically handled by the client code executing the generator. This is far
simpler than forcing the client code to firstly check whether the final
value has been yielded, and then if so, to handle that value specifically.
Generator delegation
Generators can now delegate to another generator,
Traversable object or array
automatically, without needing to write boilerplate in the outermost
generator by using the yield from construct.
Integer division with intdiv()
The new intdiv() function performs an integer division
of its operands and returns it.
Session options
session_start() now accepts an array of
options that override the
session configuration directives
normally set in php.ini.
These options have also been expanded to support
session.lazy_write, which is
on by default and causes PHP to only overwrite any session file if the
session data has changed, and read_and_close, which is
an option that can only be passed to session_start() to
indicate that the session data should be read and then the session should
immediately be closed unchanged.
For example, to set
session.cache_limiter to
private and immediately close the session after reading
it:
The new preg_replace_callback_array() function enables
code to be written more cleanly when using the
preg_replace_callback() function. Prior to PHP 7,
callbacks that needed to be executed per regular expression required the
callback function to be polluted with lots of branching.
Now, callbacks can be registered to each regular expression using an
associative array, where the key is a regular expression and the value is a
callback.
CSPRNG Functions
Two new functions have been added to generate cryptographically secure
integers and strings in a cross platform way:
random_bytes() and random_int().
list() can always unpack objects implementing
ArrayAccess
Previously, list() was not guaranteed to operate
correctly with objects implementing ArrayAccess.
This has been fixed.
Other Features
-
Class member access on cloning has been added,
e.g.
(clone $foo)->bar().