Nested or Inner Class in PHP

Question

I m building a User Class for my new website  however this time I was thinking to build it little bit differently     C    Java and even Ruby  and probably other programming languages  are allowing the use of nested inner classes inside the main class  which allows us to make the code more object-oriented and organized   In PHP  I would like to do something like so    lt  php   public class User       public  userid      public  username      private  password       public class UserProfile            some code here            private class UserHistory            some code here             gt    Is that possible in PHP  How can I achieve it     UPDATE  If it s impossible  will future PHP versions might support nested classes

User · Answer

Since PHP version 5 4 you can force create objects with private constructor through reflection  It can be used to simulate Java nested classes  Example code   class OuterClass     private  name     public function   construct  name         this- gt name    name         public function getName         return  this- gt name         public function forkInnerObject  name         class   new ReflectionClass  InnerClass         constructor    class- gt getConstructor         constructor- gt setAccessible true        innerObject    class- gt newInstanceWithoutConstructor       This method appeared in PHP 5 4      constructor- gt invoke  innerObject   this   name       return  innerObject         class InnerClass     private  parentObject    private  name     private function   construct OuterClass  parentObject   name         this- gt parentObject    parentObject       this- gt name    name         public function getName         return  this- gt name         public function getParent         return  this- gt parentObject          outerObject   new OuterClass  This is an outer object       innerObject   new InnerClass  outerObject   You cannot do it     innerObject    outerObject- gt forkInnerObject  This is an inner object    echo  innerObject- gt getName       n   echo  innerObject- gt getParent  - gt getName       n

User · Answer

It is waiting for voting as RFC  https   wiki php net rfc anonymous classes

User · Answer

You can  like this  in PHP 7   class User    public  id    public  name    public  password    public  Profile    public  History        optional declaration  if it isn t public        public function   construct  id  name  password        this- gt id  id       this- gt name  name       this- gt name  name       this- gt Profile  object            get   gt function              return  Name     this- gt name       this- gt History- gt get                              this- gt History  object            get   gt function              return   History       this- gt History- gt track                          track   gt function              return  lcg value   gt 0 5  good   bad                             echo   new User 0  Lior   nyh   - gt Profile- gt get

User · Answer

Intro   Nested classes relate to other classes a little differently than outer classes  Taking Java as an example   Non-static nested classes have access to other members of the enclosing class  even if they are declared private  Also  non-static nested classes require an instance of the parent class to be instantiated   OuterClass outerObj   new OuterClass arguments   outerObj InnerClass innerObj   outerObj new InnerClass arguments     There are several compelling reasons for using them    It is a way of logically grouping classes that are only used in one place        If a class is useful to only one other class  then it is logical to   relate and embed it in that class and keep the two together     It increases encapsulation       Consider two top-level classes  A and B  where B needs access to   members of A that would otherwise be declared private  By hiding class   B within class A  A s members can be declared private and B can access   them  In addition  B itself can be hidden from the outside world     Nested classes can lead to more readable and maintainable code       A nested class usually relates to it s parent class and together form a  package    In PHP  You can have similar behavior in PHP without nested classes    If all you want to achieve is structure organization  as Package OuterClass InnerClass  PHP namespaces might sufice  You can even declare more than one namespace in the same file  although  due to standard autoloading features  that might not be advisable    namespace  class OuterClass     namespace OuterClass  class InnerClass      If you desire to emulate other characteristics  such as member visibility  it takes a little more effort   Defining the  package  class  namespace        class Package               protect constructor so that objects can t be instantiated from outside            Since all classes inherit from Package class  they can instantiate eachother            simulating protected InnerClasses                     protected function   construct                  This magic method is called everytime an inaccessible method is called              either by visibility contrains or it doesn t exist             Here we are simulating shared protected methods across  package  classes            This method is inherited by all child classes of Package                      public function   call  method   args                   class name              class   get class  this                   we check if a method exists  if not we throw an exception                 similar to the default error                             if  method exists  this   method                         The method exists so now we want to know if the                     caller is a child of our Package class  If not we throw an exception                    Note  This is a kind of a dirty way of finding out who s                    calling the method by using debug backtrace and reflection                                       trace   debug backtrace DEBUG BACKTRACE IGNORE ARGS  3                   if  isset  trace 2                           ref   new ReflectionClass  trace 2   class                         if   ref- gt isSubclassOf   CLASS                               return  this- gt  method  args                                                           throw new  Exception  Call to private method  class   method                    else                   throw new  Exception  Call to undefined method  class   method                                          Use case  namespace Package       class MyParent extends  Package           public  publicChild          protected  protectedChild           public function   construct                   instantiate public child inside parent              this- gt publicChild   new  Package MyParent PublicChild                  instantiate protected child inside parent              this- gt protectedChild   new  Package MyParent ProtectedChild                       public function test                 echo  Call from parent - gt                  this- gt publicChild- gt protectedMethod                 this- gt protectedChild- gt protectedMethod                 echo   lt br gt Siblings lt br gt                 this- gt publicChild- gt callSibling  this- gt protectedChild                      namespace Package MyParent       class PublicChild extends  Package             Makes the constructor public  hence callable from outside          public function   construct              protected function protectedMethod                 echo  I m   get class  this    protected method lt br gt                       protected function callSibling  sibling                echo  Call from     get class  this      - gt                  sibling- gt protectedMethod                        class ProtectedChild extends  Package            protected function protectedMethod                 echo  I m   get class  this    protected method lt br gt                       protected function callSibling  sibling                echo  Call from     get class  this      - gt                  sibling- gt protectedMethod                        Testing   parent   new Package MyParent     parent- gt test     pubChild   new Package MyParent PublicChild     create new public child  possible   protChild   new Package MyParent ProtectedChild      create new protected child  ERROR    Output   Call from parent - gt  I m Package protected method I m Package protected method  Siblings Call from Package - gt  I m Package protected method Fatal error  Call to protected Package    construct   from invalid context     NOTE   I really don t think trying to emulate innerClasses in PHP is such a good idea  I think the code is less clean and readable  Also  there are probably other ways to achieve similar results using a well established pattern such as the Observer  Decorator ou COmposition Pattern  Sometimes  even simple inheritance is sufficient

User · Answer

Put each class into separate files and  require  them   User php   lt  php      class User            public  userid          public  username          private  password          public  profile          public  history                       public function   construct                  require once  UserProfile php                require once  UserHistory php                  this- gt profile   new UserProfile                 this- gt history   new UserHistory                                     gt    UserProfile php   lt  php      class UserProfile                   Some code here          gt    UserHistory php   lt  php      class UserHistory                   Some code here          gt

User · Answer

You can t do it in PHP   PHP supports  include   but you can t even do that inside of a class definition   Not a lot of great options here   This doesn t answer your question directly  but you may be interested in  Namespaces   a terribly ugly syntax hacked on top of PHP OOP  http   www php net manual en language namespaces rationale php

User · Answer

You cannot do this in PHP  However  there are functional ways to accomplish this   For more details please check this post  How to do a PHP nested class or nested methods   This way of implementation is called fluent interface  http   en wikipedia org wiki Fluent interface

User · Answer

As per Xenon s comment to Anil   zselgin s answer  anonymous classes have been implemented in PHP 7 0  which is as close to nested classes as you ll get right now   Here are the relevant RFCs   Nested Classes  status  withdrawn   Anonymous Classes  status  implemented in PHP 7 0   An example to the original post  this is what your code would look like    lt  php     public class User           public  userid          public  username          private  password           public  profile          public  history           public function   construct                  this- gt profile   new class                      Some code here for user profile                             this- gt history   new class                      Some code here for user history                                 gt    This  though  comes with a very nasty caveat   If you use an IDE such as PHPStorm or NetBeans  and then add a method like this to the User class   public function foo        this- gt profile- gt            bye bye auto-completion   This is the case even if you code to interfaces  the I in SOLID   using a pattern like this    lt  php     public class User           public  profile           public function   construct                  this- gt profile   new class implements UserProfileInterface                      Some code here for user profile                                 gt    Unless your only calls to  this- gt profile are from the   construct   method  or whatever method  this- gt profile is defined in  then you won t get any sort of type hinting   Your property is essentially  hidden  to your IDE  making life very hard if you rely on your IDE for auto-completion  code smell sniffing  and refactoring

User · Answer

Real nested classes with public protected private accessibility were proposed in 2013 for PHP 5 6 as an RFC but did not make it  No voting yet  no update since 2013 - as of 2021 02 03   https   wiki php net rfc nested classes class foo       public class bar              At least  anonymous classes made it into PHP 7 https   wiki php net rfc anonymous classes From this RFC page   Future Scope The changes made by this patch mean named nested classes are easier to implement  by a tiny bit    So  we might get nested classes in some future version  but it s not decided yet

User · Answer

I think I wrote an elegant solution to this problem by using namespaces  In my case  the inner class does not need to know his parent class  like the static inner class in Java   As an example I made a class called  User  and a subclass called  Type   used as a reference for the user types  ADMIN  OTHERS  in my example  Regards   User php  User class file    lt  php namespace          class User               private  type           public function getType    return  this- gt type           public function setType  type    this- gt type    type            namespace User       class Type               const ADMIN   0          const OTHERS   1            gt    Using php  An example of how to call the  subclass     lt  php     require once  User php           calling a subclass reference      echo  Value of user type Admin    User Type  ADMIN    gt

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