What is __ call () in php?
The call() magic function is to class functions what __get() is to class variables - if you call meow() on an object of class dog, PHP will fail to find the function and check whether you have defined a __call() function. If so, your __call() is used, with the name of the function you tried to call and the parameters you passed being passed in as parameters one and two respectively. Show Here's an example of __call() in action:
Again, note that the meow() function is commented out - if you want to be sure that __call() is not used if the function already exists, remove the comments from meow(). Want to learn PHP 7? Hacking with PHP has been fully updated for PHP 7, and is now available as a downloadable PDF. Get over 1200 pages of hands-on PHP learning today! If this was helpful, please take a moment to tell others about Hacking with PHP by tweeting about it! Next chapter: __toString() >> Previous chapter: __set() Jump to: Home: Table of Contents Copyright ©2015 Paul Hudson. Follow me: @twostraws. Magic methods are special methods which override PHP's default's action when certain actions are performed on an object. Caution All methods names starting with The following method names are considered magical: __construct(), __destruct(), __call(), __callStatic(), __get(), __set(), __isset(), __unset(), __sleep(), __wakeup(), __serialize(), __unserialize(), __toString(), __invoke(), __set_state(), __clone(), and __debugInfo(). Warning All magic methods, with the exception of __construct(), __destruct(), and
__clone(), must be declared as Warning If type declarations are used in the definition of a magic method, they must be identical to the signature described in this document. Otherwise, a fatal error is emitted. Prior to PHP 8.0.0, no diagnostic was emitted. However, __construct() and __destruct() must not declare a return type; otherwise a fatal error is emitted. __sleep() and __wakeup()public __sleep(): array public __wakeup(): void
serialize() checks if the class has a function with the magic name __sleep(). If so, that function is executed prior to any serialization. It can clean up the object and is supposed to return an array with the names of all variables of that object that should be serialized. If the method doesn't return
anything then
The intended use of __sleep() is to commit pending data or perform similar cleanup tasks. Also, the function is useful if a very large object doesn't need to be saved completely. Conversely, unserialize() checks for the presence of a function with the magic name __wakeup(). If present, this function can reconstruct any resources that the object may have. The intended use of __wakeup() is to reestablish any database connections that may have been lost during serialization and perform other reinitialization tasks. Example #1 Sleep and wakeup
__construct($dsn, $username, $password) __serialize() and __unserialize()public __serialize(): array public __unserialize(array serialize() checks if the class has a function with the magic name __serialize(). If so, that function is executed prior to any serialization. It must construct and return an associative array of key/value pairs that represent the serialized form of the object. If no array is returned a TypeError will be thrown.
The intended use of __serialize() is to define a serialization-friendly arbitrary representation of the object. Elements of the array may correspond to properties of the object but that is not required. Conversely, unserialize() checks for the presence of a function with the magic name __unserialize(). If present, this function will be passed the restored array that was returned from __serialize(). It may then restore the properties of the object from that array as appropriate.
Example #2 Serialize and unserialize
__construct($dsn, $username, $password) __toString()public __toString(): string The __toString() method allows a class to decide how it will react when it is treated like a string. For example, what Warning As of PHP 8.0.0, the return value follows standard PHP type semantics, meaning it will be coerced into a string if possible and if strict typing is disabled. As of PHP 8.0.0, any class that contains a __toString() method will also implicitly implement the Stringable interface, and will thus pass type checks for that interface. Explicitly implementing the interface anyway is recommended. In PHP 7.4, the returned value must be a string, otherwise an Error is thrown. Prior to PHP 7.4.0, the returned value must be a
string, otherwise a fatal Warning It was not possible to throw an exception from within a __toString() method prior to PHP 7.4.0. Doing so will result in a fatal error. Example #3 Simple example
__construct($foo) The above example will output: __invoke()__invoke( The __invoke() method is called when a script tries to call an object as a function. Example #4 Using __invoke()
The above example will output: Example #5 Using __invoke()
__construct(string $key) The above example will output: Array ( [0] => Array ( [id] => 3 [first_name] => Alice [last_name] => Gustav ) [1] => Array ( [id] => 2 [first_name] => Bob [last_name] => Filipe ) [2] => Array ( [id] => 1 [first_name] => John [last_name] => Do ) ) Array ( [0] => Array ( [id] => 1 [first_name] => John [last_name] => Do ) [1] => Array ( [id] => 2 [first_name] => Bob [last_name] => Filipe ) [2] => Array ( [id] => 3 [first_name] => Alice [last_name] => Gustav ) ) __set_state()static __set_state(array This static method is called for classes exported by var_export(). The only parameter of this method is an array containing exported properties in the form Example #6 Using __set_state()
__set_state($an_array) The above example will output: string(60) "A::__set_state(array( 'var1' => 5, 'var2' => 'foo', ))" object(A)#2 (2) { ["var1"]=> int(5) ["var2"]=> string(3) "foo" }
__debugInfo()__debugInfo(): array This method is called by var_dump() when dumping an object to get the properties that should be shown. If the method isn't defined on an object, then all public, protected and private properties will be shown. Example #7 Using __debugInfo()
__construct($val) { The above example will output: object(C)#1 (1) { ["propSquared"]=> int(1764) } jon at webignition dot net ¶ 13 years ago
jsnell at e-normous dot com ¶ 13 years ago
__set_state($an_array)
ctamayo at sitecrafting dot com ¶ 2 years ago
?> kguest at php dot net ¶ 5 years ago
$bar = ''; jeffxlevy at gmail dot com ¶ 17 years ago
smiley at HELLOSPAMBOT dot chillerlan dot net ¶ 6 years ago
Exception; daniel dot peder at gmail dot com ¶ 4 years ago
$shop_name; rayRO ¶ 16 years ago
__call($funcname, $args = array()) { daan dot broekhof at gmail dot com ¶ 10 years ago
(array('My_ToStringFixer', 'errorHandler')); dhuseby domain getback tld com ¶ 14 years ago
__sleep() { Wesley ¶ 11 years ago
martin dot goldinger at netserver dot ch ¶ 17 years ago
ddavenport at newagedigital dot com ¶ 17 years ago
CryptedStorageClass extends SomeStupidStorageClass yanleech at gmail dot com ¶ 14 years ago
staff at pro-unreal dot de ¶ 9 years ago
B extends A { rudie-de-hotblocks at osu1 dot php dot net ¶ 13 years ago
mastabog at hotmail dot com ¶ 17 years ago
osbertv at yahoo dot com ¶ 10 years ago
B Anonymous ¶ 12 years ago
__construct() { Dérico Filho ¶ 15 years ago
Anonymous ¶ 12 years ago
__construct($x=0, $y=0) { michal dot kocarek at seznam dot cz ¶ 14 years ago
__construct() {// All the magic is in single line: docey ¶ 16 years ago
krisj1010 at gmail.com ¶ 17 years ago
Travis Swicegood ¶ 15 years ago
__call($method, $args) danillo dot paiva dot toledo at gmail dot com ¶ 9 years ago
ricasiano at gmail dot com ¶ 1 year ago
Bar Anonymous ¶ 14 years ago
a {
tom ¶ 12 years ago
B extends A {
What is __ method __ in PHP?"Method" is basically just the name for a function within a class (or class function). Therefore __METHOD__ consists of the class name and the function name called ( dog::name ), while __FUNCTION__ only gives you the name of the function without any reference to the class it might be in.
What is __ get in PHP?From the PHP manual: __set() is run when writing data to inaccessible properties. __get() is utilized for reading data from inaccessible properties.
What is $this in PHP with example?$this is a reserved keyword in PHP that refers to the calling object. It is usually the object to which the method belongs, but possibly another object if the method is called statically from the context of a secondary object. This keyword is only applicable to internal methods.
What's the special meaning of __ sleep and __ wakeup?__sleep is supposed to return an array of the names of all variables of an object that should be serialized. __wakeup in turn will be executed by unserialize if it is present in class. It's intention is to re-establish resources and other things that are needed to be initialized upon unserialization.
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