PHP late static bindings (new static): How to ensure subclass constructor compatibility and handle divergent...
For some more complicated class hierarchy I was playin around with a minimal example for this problem a bit.
This class is given - the method "createOrUpdate()" may be modified:
class A {
protected $a;
protected $b;
protected $c;
function __construct($a,$b,$c) {
$this->a = $a;
$this->b = $b;
$this->c = $c;
}
public static function createOrUpdate($a,$b,$c) {
if(self::exists($b)) {
someWhateverUpdate();
} else {
new static($a,$b,$c);
}
}
}
Now lets see what happens if we extend it:
class B extends A {
function __construct($a,$b,$c) {
parent::__construct($a,$b,$c);
}
}
B::createOrUpdate("rock","this","now");
Works fine!
class C extends B {
function __construct($a,$b) {
parent::__construct($a,$b,"exactly");
}
}
C::createOrUpdate("rock","this","now");
Works also fine however if somebody does createOrUpdate() parameter $c
is lost silently!
class D extends A {
protected $d;
function __construct($a,$b,$c,$d) {
$this->a = $a;
$this->b = $b;
$this->c = $c;
$this->d = $d;
}
}
D::createOrUpdate("rock","this","now");
Error: Throws ArgumentCountError
class E extends A {
function __construct($b,$c) {
$this->a = "Lorem";
$this->b = $b;
$this->c = $c;
}
}
D::createOrUpdate("rock","this","now");
Error: Works but will behave completely unexpected.
Now my question is: Can I use some reflection within createOrUpdate()
in order to check if the current subclass called is implementing the constructor correctly? How would you handle this if somebody else may implement further subclasses within the hierarchy?
php inheritance constructor static late-static-binding
add a comment |
For some more complicated class hierarchy I was playin around with a minimal example for this problem a bit.
This class is given - the method "createOrUpdate()" may be modified:
class A {
protected $a;
protected $b;
protected $c;
function __construct($a,$b,$c) {
$this->a = $a;
$this->b = $b;
$this->c = $c;
}
public static function createOrUpdate($a,$b,$c) {
if(self::exists($b)) {
someWhateverUpdate();
} else {
new static($a,$b,$c);
}
}
}
Now lets see what happens if we extend it:
class B extends A {
function __construct($a,$b,$c) {
parent::__construct($a,$b,$c);
}
}
B::createOrUpdate("rock","this","now");
Works fine!
class C extends B {
function __construct($a,$b) {
parent::__construct($a,$b,"exactly");
}
}
C::createOrUpdate("rock","this","now");
Works also fine however if somebody does createOrUpdate() parameter $c
is lost silently!
class D extends A {
protected $d;
function __construct($a,$b,$c,$d) {
$this->a = $a;
$this->b = $b;
$this->c = $c;
$this->d = $d;
}
}
D::createOrUpdate("rock","this","now");
Error: Throws ArgumentCountError
class E extends A {
function __construct($b,$c) {
$this->a = "Lorem";
$this->b = $b;
$this->c = $c;
}
}
D::createOrUpdate("rock","this","now");
Error: Works but will behave completely unexpected.
Now my question is: Can I use some reflection within createOrUpdate()
in order to check if the current subclass called is implementing the constructor correctly? How would you handle this if somebody else may implement further subclasses within the hierarchy?
php inheritance constructor static late-static-binding
add a comment |
For some more complicated class hierarchy I was playin around with a minimal example for this problem a bit.
This class is given - the method "createOrUpdate()" may be modified:
class A {
protected $a;
protected $b;
protected $c;
function __construct($a,$b,$c) {
$this->a = $a;
$this->b = $b;
$this->c = $c;
}
public static function createOrUpdate($a,$b,$c) {
if(self::exists($b)) {
someWhateverUpdate();
} else {
new static($a,$b,$c);
}
}
}
Now lets see what happens if we extend it:
class B extends A {
function __construct($a,$b,$c) {
parent::__construct($a,$b,$c);
}
}
B::createOrUpdate("rock","this","now");
Works fine!
class C extends B {
function __construct($a,$b) {
parent::__construct($a,$b,"exactly");
}
}
C::createOrUpdate("rock","this","now");
Works also fine however if somebody does createOrUpdate() parameter $c
is lost silently!
class D extends A {
protected $d;
function __construct($a,$b,$c,$d) {
$this->a = $a;
$this->b = $b;
$this->c = $c;
$this->d = $d;
}
}
D::createOrUpdate("rock","this","now");
Error: Throws ArgumentCountError
class E extends A {
function __construct($b,$c) {
$this->a = "Lorem";
$this->b = $b;
$this->c = $c;
}
}
D::createOrUpdate("rock","this","now");
Error: Works but will behave completely unexpected.
Now my question is: Can I use some reflection within createOrUpdate()
in order to check if the current subclass called is implementing the constructor correctly? How would you handle this if somebody else may implement further subclasses within the hierarchy?
php inheritance constructor static late-static-binding
For some more complicated class hierarchy I was playin around with a minimal example for this problem a bit.
This class is given - the method "createOrUpdate()" may be modified:
class A {
protected $a;
protected $b;
protected $c;
function __construct($a,$b,$c) {
$this->a = $a;
$this->b = $b;
$this->c = $c;
}
public static function createOrUpdate($a,$b,$c) {
if(self::exists($b)) {
someWhateverUpdate();
} else {
new static($a,$b,$c);
}
}
}
Now lets see what happens if we extend it:
class B extends A {
function __construct($a,$b,$c) {
parent::__construct($a,$b,$c);
}
}
B::createOrUpdate("rock","this","now");
Works fine!
class C extends B {
function __construct($a,$b) {
parent::__construct($a,$b,"exactly");
}
}
C::createOrUpdate("rock","this","now");
Works also fine however if somebody does createOrUpdate() parameter $c
is lost silently!
class D extends A {
protected $d;
function __construct($a,$b,$c,$d) {
$this->a = $a;
$this->b = $b;
$this->c = $c;
$this->d = $d;
}
}
D::createOrUpdate("rock","this","now");
Error: Throws ArgumentCountError
class E extends A {
function __construct($b,$c) {
$this->a = "Lorem";
$this->b = $b;
$this->c = $c;
}
}
D::createOrUpdate("rock","this","now");
Error: Works but will behave completely unexpected.
Now my question is: Can I use some reflection within createOrUpdate()
in order to check if the current subclass called is implementing the constructor correctly? How would you handle this if somebody else may implement further subclasses within the hierarchy?
php inheritance constructor static late-static-binding
php inheritance constructor static late-static-binding
edited Nov 13 '18 at 14:31
Blackbam
asked Nov 13 '18 at 14:19
BlackbamBlackbam
5,046124175
5,046124175
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
How about if you implement interface to your A class?
interface interfaceA {
public function __construct($a, $b, $c);
}
class A implements interfaceA
{
...
}
This will force every extending class to either not have constructor or implement the one matching on class A or PHP Fatal error: Declaration of B::__construct($a, $b) must be compatible with interfaceA::__construct($a, $b, $c)
will be thrown.
You can also add public static function createOrUpdate($a, $b, $c);
to the interface to force all extending classes to implement such method.
Thanks I like the idea on putting an interface on top of the hierarchy. Making createOrUpdate abstract is also a good idea if code reuse can be neglected however in this case I want it.
– Blackbam
Nov 13 '18 at 14:45
add a comment |
After experimenting a bit further also with the input of @nforced I found another good solution - make the constructor protected and final. Now subclasses are forced to implement a creation method (e.g. create()
) which is using the desired constructor.
class A {
protected $a;
protected $b;
protected $c;
protected final function __construct($a,$b,$c) {
$this->a = $a;
$this->b = $b;
$this->c = $c;
}
public static function createOrUpdate($a,$b,$c) {
if(self::exists($b)) {
updateMe();
} else {
new static($a,$b,$c);
}
}
}
You can also doabstract class A
withabstract public static function createOrUpdate($a,$b,$c);
to force subclasses to implement this method.
– nforced
Nov 13 '18 at 15:10
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
How about if you implement interface to your A class?
interface interfaceA {
public function __construct($a, $b, $c);
}
class A implements interfaceA
{
...
}
This will force every extending class to either not have constructor or implement the one matching on class A or PHP Fatal error: Declaration of B::__construct($a, $b) must be compatible with interfaceA::__construct($a, $b, $c)
will be thrown.
You can also add public static function createOrUpdate($a, $b, $c);
to the interface to force all extending classes to implement such method.
Thanks I like the idea on putting an interface on top of the hierarchy. Making createOrUpdate abstract is also a good idea if code reuse can be neglected however in this case I want it.
– Blackbam
Nov 13 '18 at 14:45
add a comment |
How about if you implement interface to your A class?
interface interfaceA {
public function __construct($a, $b, $c);
}
class A implements interfaceA
{
...
}
This will force every extending class to either not have constructor or implement the one matching on class A or PHP Fatal error: Declaration of B::__construct($a, $b) must be compatible with interfaceA::__construct($a, $b, $c)
will be thrown.
You can also add public static function createOrUpdate($a, $b, $c);
to the interface to force all extending classes to implement such method.
Thanks I like the idea on putting an interface on top of the hierarchy. Making createOrUpdate abstract is also a good idea if code reuse can be neglected however in this case I want it.
– Blackbam
Nov 13 '18 at 14:45
add a comment |
How about if you implement interface to your A class?
interface interfaceA {
public function __construct($a, $b, $c);
}
class A implements interfaceA
{
...
}
This will force every extending class to either not have constructor or implement the one matching on class A or PHP Fatal error: Declaration of B::__construct($a, $b) must be compatible with interfaceA::__construct($a, $b, $c)
will be thrown.
You can also add public static function createOrUpdate($a, $b, $c);
to the interface to force all extending classes to implement such method.
How about if you implement interface to your A class?
interface interfaceA {
public function __construct($a, $b, $c);
}
class A implements interfaceA
{
...
}
This will force every extending class to either not have constructor or implement the one matching on class A or PHP Fatal error: Declaration of B::__construct($a, $b) must be compatible with interfaceA::__construct($a, $b, $c)
will be thrown.
You can also add public static function createOrUpdate($a, $b, $c);
to the interface to force all extending classes to implement such method.
edited Nov 13 '18 at 14:53
answered Nov 13 '18 at 14:35
nforcednforced
91112
91112
Thanks I like the idea on putting an interface on top of the hierarchy. Making createOrUpdate abstract is also a good idea if code reuse can be neglected however in this case I want it.
– Blackbam
Nov 13 '18 at 14:45
add a comment |
Thanks I like the idea on putting an interface on top of the hierarchy. Making createOrUpdate abstract is also a good idea if code reuse can be neglected however in this case I want it.
– Blackbam
Nov 13 '18 at 14:45
Thanks I like the idea on putting an interface on top of the hierarchy. Making createOrUpdate abstract is also a good idea if code reuse can be neglected however in this case I want it.
– Blackbam
Nov 13 '18 at 14:45
Thanks I like the idea on putting an interface on top of the hierarchy. Making createOrUpdate abstract is also a good idea if code reuse can be neglected however in this case I want it.
– Blackbam
Nov 13 '18 at 14:45
add a comment |
After experimenting a bit further also with the input of @nforced I found another good solution - make the constructor protected and final. Now subclasses are forced to implement a creation method (e.g. create()
) which is using the desired constructor.
class A {
protected $a;
protected $b;
protected $c;
protected final function __construct($a,$b,$c) {
$this->a = $a;
$this->b = $b;
$this->c = $c;
}
public static function createOrUpdate($a,$b,$c) {
if(self::exists($b)) {
updateMe();
} else {
new static($a,$b,$c);
}
}
}
You can also doabstract class A
withabstract public static function createOrUpdate($a,$b,$c);
to force subclasses to implement this method.
– nforced
Nov 13 '18 at 15:10
add a comment |
After experimenting a bit further also with the input of @nforced I found another good solution - make the constructor protected and final. Now subclasses are forced to implement a creation method (e.g. create()
) which is using the desired constructor.
class A {
protected $a;
protected $b;
protected $c;
protected final function __construct($a,$b,$c) {
$this->a = $a;
$this->b = $b;
$this->c = $c;
}
public static function createOrUpdate($a,$b,$c) {
if(self::exists($b)) {
updateMe();
} else {
new static($a,$b,$c);
}
}
}
You can also doabstract class A
withabstract public static function createOrUpdate($a,$b,$c);
to force subclasses to implement this method.
– nforced
Nov 13 '18 at 15:10
add a comment |
After experimenting a bit further also with the input of @nforced I found another good solution - make the constructor protected and final. Now subclasses are forced to implement a creation method (e.g. create()
) which is using the desired constructor.
class A {
protected $a;
protected $b;
protected $c;
protected final function __construct($a,$b,$c) {
$this->a = $a;
$this->b = $b;
$this->c = $c;
}
public static function createOrUpdate($a,$b,$c) {
if(self::exists($b)) {
updateMe();
} else {
new static($a,$b,$c);
}
}
}
After experimenting a bit further also with the input of @nforced I found another good solution - make the constructor protected and final. Now subclasses are forced to implement a creation method (e.g. create()
) which is using the desired constructor.
class A {
protected $a;
protected $b;
protected $c;
protected final function __construct($a,$b,$c) {
$this->a = $a;
$this->b = $b;
$this->c = $c;
}
public static function createOrUpdate($a,$b,$c) {
if(self::exists($b)) {
updateMe();
} else {
new static($a,$b,$c);
}
}
}
answered Nov 13 '18 at 14:59
BlackbamBlackbam
5,046124175
5,046124175
You can also doabstract class A
withabstract public static function createOrUpdate($a,$b,$c);
to force subclasses to implement this method.
– nforced
Nov 13 '18 at 15:10
add a comment |
You can also doabstract class A
withabstract public static function createOrUpdate($a,$b,$c);
to force subclasses to implement this method.
– nforced
Nov 13 '18 at 15:10
You can also do
abstract class A
with abstract public static function createOrUpdate($a,$b,$c);
to force subclasses to implement this method.– nforced
Nov 13 '18 at 15:10
You can also do
abstract class A
with abstract public static function createOrUpdate($a,$b,$c);
to force subclasses to implement this method.– nforced
Nov 13 '18 at 15:10
add a comment |
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