How do I get a PHP class constructor to call its parent s parent s constructor

Question

I need to have a class constructor in PHP call its parent s parent s  grandparent   constructor without calling the parent constructor      main class that everything inherits class Grandpa        public function   construct                    class Papa extends Grandpa       public function   construct                    call Grandpa s constructor         parent    construct             class Kiddo extends Papa       public function   construct                    THIS IS WHERE I NEED TO CALL GRANDPA S            CONSTRUCTOR AND NOT PAPA S           I know this is a bizarre thing to do and I m attempting to find a means that doesn t smell bad but nonetheless  I m curious if it s possible

User · Answer

from php 7 u can use   parent  parent    construct

User · Answer

main class that everything inherits class Grandpa        public function   construct                  this- gt    construct               protected function    construct                    grandpa s logic           class Papa extends Grandpa       public function   construct                    call Grandpa s constructor         parent    construct             class Kiddo extends Papa       public function   construct                 parent     construct              note that     construct  is not some magic name  you can call it  doGrandpaStuff

User · Answer

class Grandpa        public function   construct             class Papa extends Grandpa       public function   construct                   call Grandpa s constructor         parent    construct             class Kiddo extends Papa       public function   construct                   this is not a bug  it works that way in php         Grandpa    construct

User · Answer

There s an easier solution for this  but it requires that you know exactly how much inheritance your current class has gone through   Fortunately  get parent class   s arguments allow your class array member to be the class name as a string as well as an instance itself   Bear in mind that this also inherently relies on calling a class    construct   method statically  though within the instanced scope of an inheriting object the difference in this particular case is negligible  ah  PHP    Consider the following   class Foo       var  f    bad  Foo         function   construct              this- gt f    Good             class Bar extends Foo       var  f    bad  Bar       class FooBar extends Bar       var  f    bad  FooBar         function   construct               FooBar constructor logic here         call user func array get parent class get parent class  this       construct               foo   new FooBar    echo  foo- gt f     gt   Good     Again  this isn t a viable solution for a situation where you have no idea how much inheritance has taken place  due to the limitations of debug backtrace    but in controlled circumstances  it works as intended

User · Answer

I agree with  too much php   try this   class Grandpa        public function   construct                 echo  Grandpa lt br  gt              class Papa extends Grandpa       public function   construct                 echo  Papa lt br  gt            parent    construct             class Kiddo extends Papa       public function   construct                    THIS IS WHERE I NEED TO CALL GRANDPA S            CONSTRUCTOR AND NOT PAPA S         echo  Kiddo lt br  gt            Grandpa    construct              instance   new Kiddo    I got the result as expected           Kiddo          Grandpa      This is a feature not a bug  check this for your reference   https   bugs php net bug php id 42016          It is just the way it works  If it sees it is coming from the right context this call version does not enforce a static call           Instead it will simply keep  this and be happy with it       parent  method   works in the same way  you don t have to define the method as static but it can be called in the same context  Try this out for more interesting   class Grandpa        public function   construct                 echo  Grandpa lt br  gt            Kiddo  hello              class Papa extends Grandpa       public function   construct                 echo  Papa lt br  gt            parent    construct             class Kiddo extends Papa       public function   construct                    THIS IS WHERE I NEED TO CALL GRANDPA S            CONSTRUCTOR AND NOT PAPA S         echo  Kiddo lt br  gt            Grandpa    construct               public function hello                 echo  Hello lt br  gt              instance   new Kiddo    It also works as expected           Kiddo          Grandpa          Hello      But if you try to initialize a new Papa  you will get an E STRICT error    papa   new Papa            Strict standards  Non-static method Kiddo  hello   should not be called statically  assuming  this from incompatible context      You can use instanceof to determine if you can call a Children  method   in a parent method   if   this instanceof Kiddo  Kiddo  hello

User · Answer

The ugly workaround would be to pass a boolean param to Papa indicating that you do not wish to parse the code contained in it s constructor   i e      main class that everything inherits class Grandpa        public function   construct                    class Papa extends Grandpa       public function   construct  bypass   false                   only perform actions inside if not bypassing         if    bypass                          call Grandpa s constructor         parent    construct             class Kiddo extends Papa       public function   construct                  bypassPapa   true          parent    construct  bypassPapa

User · Answer

Funny detail about php  extended classes can use non-static functions of a parent class in a static matter  Outside you will get a strict error   error reporting E ALL    class GrandPa       public function   construct                 print  construct grandpa lt br  gt              this- gt grandPaFkt               protected function grandPaFkt            print   gt  gt do Grandpa lt br  gt              class Pa extends GrandPa       public function   construct           parent    construct            print  construct Pa  lt br  gt                public function paFkt            print   gt  gt do Pa  lt br gt              class Child extends Pa       public function   construct                 GrandPa    construct            Pa  paFkt     allright           parent    construct     whatever you want         print  construct Child lt br  gt                test new Child     test  paFkt     strict error    So inside a extended class  Child  you can use   parent  paFkt       or   Pa  paFkt      to access a parent  or grandPa s   not private  function    Outside class def    test  paFkt      will trow strict error  non static function

User · Answer

You must use Grandpa    construct    there s no other shortcut for it  Also  this ruins the encapsulation of the Papa class - when reading or working on Papa  it should be safe to assume that the   construct   method will be called during construction  but the Kiddo class does not do this

User · Answer

You can call Grandpa    construct from where you want and the  this keyword will refer to your current class instance  But be carefull with this method you cannot access to protected properties and methods of current instance from this other context  only to public elements     All work and officialy supported   Example     main class that everything inherits class Grandpa        public function   construct                 echo  this- gt one     will print 1         echo  this- gt two     error cannot access protected property           class Papa extends Grandpa       public function   construct                    call Grandpa s constructor         parent    construct             class Kiddo extends Papa       public  one   1      protected  two   2      public function   construct                 Grandpa    construct             new Kiddo

User · Answer

class Grandpa        public function   construct                 echo Hello Kiddo                class Papa extends Grandpa       public function   construct                               public function CallGranddad                 parent    construct             class Kiddo extends Papa       public function   construct                    public function needSomethingFromGrandDad              parent  CallGranddad

User · Answer

lt  php  class grand pa       public function   construct                 echo  Hey I am Grand Pa  lt br gt             class pa pa extends grand pa          no need for construct here unless you want to do something specifically within this class as init stuff        the construct for this class will be inherited from the parent     class kiddo extends pa pa       public function   construct                 parent    construct            echo  Hey I am a child  lt br gt             new kiddo      gt    Of course this expects you do not need to do anything within the construct of the pa pa  Running this will output    Hey I am Grand Pa Hey I am a child

User · Answer

Another option that doesn t use a flag and might work in your situation    lt  php    main class that everything inherits class Grandpa        public function   construct             this- gt GrandpaSetup               public function GrandpaSetup             this- gt prop1    foo            this- gt prop2    bar            class Papa extends Grandpa       public function   construct                    call Grandpa s constructor         parent    construct             this- gt prop1    foobar            class Kiddo extends Papa       public function   construct                  this- gt GrandpaSetup              kid   new Kiddo    echo    kid- gt prop1  n  kid- gt prop2  n

User · Answer

Ok  Yet another ugly solution   Create a function in Papa like   protected function call2Granpa          return parent    construct        Then in Kiddo you use   parent  call2Granpa      instead of calling constructor in Papa   I think it could work    I haven t test it  so I m not sure if the objects are created correctly    I used this approach but with non-constructor functions

User · Answer

Beautiful solution using Reflection    lt  php class Grandpa        public function   construct                 echo  Grandpa s constructor called n             class Papa extends Grandpa       public function   construct                 echo  Papa s constructor called n               call Grandpa s constructor         parent    construct             class Kiddo extends Papa       public function   construct                 echo  Kiddo s constructor called n             reflectionMethod   new ReflectionMethod get parent class get parent class  this       construct             reflectionMethod- gt invoke  this             kiddo   new Kiddo     papa   new Papa

User · Answer

I ended up coming up with an alternative solution that solved the problem    I created an intermediate class that extended Grandpa  Then both Papa and Kiddo extended that class  Kiddo required some intermediate functionality of Papa but didn t like it s constructor so the class has that additional functionality and both extend it    I ve upvoted the other two answers that provided valid yet ugly solutions for an uglier question

[php] How do I get a PHP class constructor to call its parent's parent's constructor?

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