PHP Constants Containing Arrays

Question

This failed    define  DEFAULT ROLES   array  guy    development team       Apparently  constants can t hold arrays  What is the best way to get around this   define  DEFAULT ROLES    guy development team             default   explode      DEFAULT ROLES     This seems like unnecessary effort

User · Answer

Doing some sort of ser deser or encode decode trick seems ugly and requires you to remember what exactly you did when you are trying to use the constant   I think the class private static variable with accessor is a decent solution  but I ll do you one better   Just have a public static getter method that returns the definition of the constant array   This requires a minimum of extra code and the array definition cannot be accidentally modified   class UserRoles       public static function getDefaultRoles             return array  guy    development team             initMyRoles  UserRoles  getDefaultRoles        If you want to really make it look like a defined constant you could give it an all caps name  but then it would be confusing to remember to add the      parentheses after the name   class UserRoles       public static function DEFAULT ROLES     return array  guy    development team           but  then the extra    looks weird    initMyRoles  UserRoles  DEFAULT ROLES        I suppose you could make the method global to be closer to the define   functionality you were asking for  but you really should scope the constant name anyhow and avoid globals

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Constants can only contain scalar values  I suggest you store the serialization  or JSON encoded representation  of the array

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Can even work with Associative Arrays   for example in a class   class Test        const          CAN                  can bark    can meow    can fly                     ANIMALS                 self  CAN 0    gt   dog               self  CAN 1    gt   cat               self  CAN 2    gt   bird                  static function noParameter             return self  ANIMALS self  CAN 0               static function withParameter  which   animal            return  who   which   a   animal               echo Test  noParameter      s     Test  CAN 0       lt br gt    echo Test  withParameter      array keys Test  ANIMALS  2   Test  ANIMALS  can fly          dogs can bark     who can fly  a bird

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Starting with PHP 5 6  you can define constant arrays using const keyword like below  const DEFAULT ROLES     test    development    team      and different elements can be accessed as below    echo DEFAULT ROLES 1           Starting with PHP 7  constant arrays can be defined using define as below    define  DEFAULT ROLES          test        development        team        and different elements can be accessed same way as before

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You can define like this  define  GENERIC DOMAIN  json encode array       gmail com   gmail co in   yahoo com         domains   json decode GENERIC DOMAIN   var dump  domains

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This is what I use  It is similar to the example provided by soulmerge  but this way you can get the full array or just a single value in the array   class Constants       private static  array   array 0   gt   apple   1   gt   orange         public static function getArray  index   false            return  index     false   self   array  index    self   array            Use it like this   Constants  getArray       Full array    OR  Constants  getArray 1      Value of 1 which is  orange

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If you are using PHP 5 6 or above  use Andrea Faulds answer   I am using it like this  I hope  it will help others   config php  class app      private static  options   array           app id    gt   hello              public static function config  key           return self   options  key             In file  where I need constants   require  config php    print r app  config  app id

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You can store it as a JSON string in a constant  And application point of view  JSON can be useful in other cases   define   FRUITS   json encode array   apple    cherry    banana           fruits   json decode  FRUITS       var dump  fruits

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I know it s a bit old question  but here is my solution    lt  php class Constant        private  data            public function define  constant   value            if   isset  this- gt data  constant                   this- gt data  constant     value            else               trigger error  Cannot redefine constant  constant   E USER WARNING                        public function   get  constant            if  isset  this- gt data  constant                  return  this- gt data  constant             else               trigger error  Use of undefined constant  constant - assumed   constant    E USER NOTICE               return  constant                       public function   set  constant  value             this- gt define  constant   value             const   new Constant    I defined it because I needed to store objects and arrays in constants so I installed also runkit to php so I could make the  const variable superglobal   You can use it as  const- gt define  my constant  array  my   values     or just  const- gt my constant   array  my   values     To get the value just simply call  const- gt my constant

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Using explode and implode function we can improvise a solution     array   array  lastname    email    phone    define  DEFAULT ROLES   implode         array    echo explode      DEFAULT ROLES    1      This will echo email   If you want it to optimize it more you can define 2 functions to do the repetitive things for you like this      function to define constant function custom define   const    array        define  const  implode         array         function to access constant   function return by index   index  const   DEFAULT ROLES                 explodedResult   explode       const     index       if  isset   explodedResult           return explode       const     index        Hope that helps   Happy coding

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You can store them as static variables of a class   class Constants       public static  array   array  guy    development team        Warning  array can be changed lateron  so this is not a real constant value  Constants   array      newValue     If you don t like the idea that the array can be changed by others  a getter might help   class Constants       private static  array   array  guy    development team        public static function getArray             return self   array           constantArray   Constants  getArray      EDIT  Since PHP5 4  it is even possible to access array values without the need for intermediate variables  i e  the following works    x   Constants  getArray    index

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NOTE  while this is the accepted answer  it s worth noting that in PHP 5 6  you can have const arrays - see Andrea Faulds  answer below   You can also serialize your array and then put it into the constant     define constant  serialize array define   FRUITS   serialize  array   apple    cherry    banana         use it  my fruits   unserialize  FRUITS

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PHP 7   As of PHP 7  you can just use the define   function to define a constant array    define  ANIMALS          dog        cat        bird       echo ANIMALS 1      outputs  cat

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Since PHP 5 6  you can declare an array constant with const    lt  php const DEFAULT ROLES   array  guy    development team      The short syntax works too  as you d expect    lt  php const DEFAULT ROLES     guy    development team      If you have PHP 7  you can finally use define    just as you had first tried    lt  php define  DEFAULT ROLES   array  guy    development team

User · Answer

Yes  You can define an array as constant  From PHP 5 6 onwards  it is possible to define a constant as a scalar expression  and it is also possible to define an array constant  It is possible to define constants as a resource  but it should be avoided  as it can cause unexpected results    lt  php        Works as of PHP 5 3 0     const CONSTANT    Hello World       echo CONSTANT          Works as of PHP 5 6 0     const ANOTHER CONST   CONSTANT    Goodbye World       echo ANOTHER CONST       const ANIMALS   array  dog    cat    bird        echo ANIMALS 1      outputs  cat          Works as of PHP 7     define  ANIMALS   array           dog            cat            bird              echo ANIMALS 1      outputs  cat    gt    With the reference of this link   Have a happy coding

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if you re using PHP 7  amp  7   you can use fetch like this as well  define  TEAM     guy    development team     echo TEAM 0       output from system will be  guy

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If you are looking this from 2009  and you don t like AbstractSingletonFactoryGenerators  here are a few other options   Remember  arrays are  copied  when assigned  or in this case  returned  so you are practically getting the same array every time   See copy-on-write behaviour of arrays in PHP    function FRUITS ARRAY      return array  chicken    mushroom    dirt       function FRUITS ARRAY      static  array   array  chicken    mushroom    dirt      return  array     function WHAT ANIMAL   key      static  array          Merrick    gt   Elephant        Sprague    gt   Skeleton        Shaun      gt   Sheep          return  array   key       function ANIMAL   key   null      static  array          Merrick    gt   Elephant        Sprague    gt   Skeleton        Shaun      gt   Sheep          return  key     null    array   key      array

[php] PHP Constants Containing Arrays?

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