How to initialize static variables

Question

I have this code   private static  dates   array     start    gt  mktime  0   0   0   7  30  2009       Start date    end      gt  mktime  0   0   0   8   2  2009       End date    close    gt  mktime 23  59  59   7  20  2009       Date when registration closes    early    gt  mktime  0   0   0   3  19  2009       Date when early bird discount ends      Which gives me the following error      Parse error  syntax error  unexpected      expecting     in  home user Sites site registration inc registration class inc on line 19   So  I guess I am doing something wrong    but how can I do this if not like that  If I change the mktime stuff with regular strings  it works  So I know that I can do it sort of like that    Anyone have some pointers

User · Accepted Answer

PHP can t parse non-trivial expressions in initializers   I prefer to work around this by adding code right after definition of the class   class Foo     static  bar    Foo   bar   array         or  class Foo     private static  bar    static function init           self   bar   array             Foo  init        PHP 5 6 can handle some expressions now      For Abstract classes    abstract class Foo      private static function bar            static  bar   null          if   bar    null              bar   array               return  bar               use where necessary        self  bar

User · Answer

If you have control over class loading  you can do static initializing from there   Example   class MyClass   public static function static init           in your class loader  do the following   include  path    klass   PHP EXT   if method exists  klass   static init       klass  staticInit       A more heavy weight solution would be to use an interface with ReflectionClass   interface StaticInit   public static function staticInit         class MyClass implements StaticInit   public static function staticInit           in your class loader  do the following    rc   new ReflectionClass  klass   if in array  StaticInit    rc- gt getInterfaceNames        klass  staticInit

User · Answer

Instead of finding a way to get static variables working  I prefer to simply create a getter function  Also helpful if you need arrays belonging to a specific class  and a lot simpler to implement   class MyClass      public static function getTypeList               return array              type a   gt  Type A               type b   gt  Type B                    etc                     Wherever you need the list  simply call the getter method  For example   if  array key exists  type  MyClass  getTypeList              do something important

User · Answer

That s too complex to set in the definition  You can set the definition to null though  and then in the constructor  check it  and if it has not been changed - set it   private static  dates   null  public function   construct         if  is null self   dates         OR if   is array self   date            self   dates   array

User · Answer

You can t make function calls in this part of the code   If you make an init   type method that gets executed before any other code does then you will be able to populate the variable then

User · Answer

In PHP 7 0 1  I was able to define this    public static  kIdsByActions   array    MyClass1  kAction   gt  0    MyClass2  kAction   gt  1      And then use it like this   MyClass   kIdsByActions  this- gt mAction

User · Answer

I use a combination of Tjeerd Visser s and porneL s answer   class Something       private static  foo       private static getFoo                 if   foo     null               foo      complicated initializer            return  foo             public static bar                    do something with self  getFoo                But an even better solution is to do away with the static methods and use the Singleton pattern  Then you just do the complicated initialization in the constructor  Or make it a  service  and use DI to inject it into any class that needs it

User · Answer

Here is a hopefully helpful pointer  in a code example   Note how the initializer function is only called once   Also  if you invert the calls to StaticClass  initializeStStateArr   and  st   new StaticClass   you ll get the same result     cat static php  lt  php  class StaticClass      public static   stStateArr   NULL     public function   construct         if   isset self   stStateArr           self  initializeStStateArr                 public static function initializeStStateArr         if   isset self   stStateArr           self   stStateArr   array  CA    gt   California    CO    gt   Colorado           echo  In       FUNCTION      n                 print  Starting    n   StaticClass  initializeStStateArr     st   new StaticClass     print r  StaticClass   stStateArr     Which yields      php static php Starting    In initializeStStateArr Array        CA    gt  California      CO    gt  Colorado

User · Answer

best way is to create an accessor like this          var object  db   map to database connection     public static  db  null          db Function for initializing variable        return object    public static function db     if   isset static   db       static   db  new  Helpers MySQL  array       hostname   gt   localhost        username   gt   root        password   gt   password        database   gt   db name                 return static   db      then you can do static  db    or self  db    from anywhere

[php] How to initialize static variables

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