PHP Accessing Parent Class Variable

Question

class A       private  aa      protected  bb    parent bb        function   construct  arg             do something              private function parentmethod  arg2             do something            class B extends A       function   construct  arg            parent    construct  arg             function childfunction             echo parent   bb    Fatal error  Undefined class constant  bb             test   new B  some    test- gt childfunction      Question  How do I display parent variable in child  expected result will echo  parent bb

User · Answer

With parent   bb  you try to retrieve the static constant defined with the value of  bb   Instead  do   echo  this- gt bb    Note  you don t need to call parent   construct if B is the only class that calls it  Simply don t declare   construct in B class

User · Answer

bb has now become the private member of class B after extending class A where it was protected   So you access  bb like it s an attribute of class B   class A       private  aa      protected  bb    parent bb        function   construct  arg             do something              private function parentmethod  arg2             do something            class B extends A       function   construct  arg            parent    construct  arg             function childfunction             echo  this- gt bb             test   new B  some    test- gt childfunction

User · Answer

class A       private  aa      protected  bb    parent bb        function   construct  arg             do something              private function parentmethod  arg2             do something            class B extends A       function   construct  arg            parent    construct  arg             function childfunction             echo parent   this- gt bb    works by M           test   new B  some    test- gt childfunction

User · Answer

Just echo it since it s inherited  echo  this- gt bb

User · Answer

all the properties and methods of the parent class is inherited in the child class so theoretically you can access them in the child class but beware using the protected keyword in your class because it throws a fatal error when used in the child class  as mentioned in php net      The visibility of a property or method   can be defined by prefixing the   declaration with the keywords public    protected or private  Class members   declared public can be accessed   everywhere  Members declared protected   can be accessed only within the class   itself and by inherited and parent   classes  Members declared as private   may only be accessed by the class that   defines the member

User · Answer

echo  this- gt bb    The variable is inherited and is not private  so it is a part of the current object     Here is additional information in response to your request for more information about using parent     Use parent   when you want add extra functionality to a method from the parent class  For example  imagine an Airplane class   class Airplane       private  pilot       public function   construct   pilot              this- gt pilot    pilot            Now suppose we want to create a new type of Airplane that also has a navigator  You can extend the   construct   method to add the new functionality  but still make use of the functionality offered by the parent   class Bomber extends Airplane       private  navigator       public function   construct   pilot   navigator              this- gt navigator    navigator           parent    construct   pilot       Assigns  pilot to  this- gt pilot           In this way  you can follow the DRY principle of development but still provide all of the functionality you desire

[php] PHP Accessing Parent Class Variable

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