Reputation: 158351
I have this code:
private static $dates = array(
'start' => mktime( 0, 0, 0, 7, 30, 2009), // Start date
'end' => mktime( 0, 0, 0, 8, 2, 2009), // End date
'close' => mktime(23, 59, 59, 7, 20, 2009), // Date when registration closes
'early' => 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?
Upvotes: 221
Views: 225819
Reputation: 175
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 dependency injection to inject it into any class that needs it.
Upvotes: 13
Reputation: 1677
In my case, I'm using both static and nonstatic class properties, and I might even have main program code referencing the static part of the class before defining the class. Since static portions of classes don't have constructors, just add a manual constructor to initialize any variables requiring nontrivial calculation:
class A
{
static $a; // Initialized by Init()
static function Init()
{
A::$a=nontrivial();
{
}
...
A::Init(); // Initialize static part of class
...
$obj=new A(); // Using initialized class as an object
Upvotes: 0
Reputation: 100220
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();
}
Upvotes: 360
Reputation: 4052
In PHP 7.0.1, I was able to define this:
public static $kIdsByActions = array(
MyClass1::kAction => 0,
MyClass2::kAction => 1
);
And then use it like this:
MyClass::$kIdsByActions[$this->mAction];
Upvotes: 4
Reputation: 348
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::$db= new \Helpers\MySQL( array(
"hostname"=> "localhost",
"username"=> "root",
"password"=> "password",
"database"=> "db_name"
)
);
}
return static::$db;
}
then you can do static::db(); or self::db(); from anywhere.
Upvotes: 4
Reputation: 129
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
<?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' => 'California', 'CO' => '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] => California
[CO] => Colorado
)
Upvotes: -1
Reputation: 465
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"=>"Type A",
"type_b"=>"Type B",
//... etc.
);
}
}
Wherever you need the list, simply call the getter method. For example:
if (array_key_exists($type, MyClass::getTypeList()) {
// do something important...
}
Upvotes: 24
Reputation: 1408
If you have control over class loading, you can do static initializing from there.
Example:
class MyClass { public static function static_init() { } }
in your class loader, do the following:
include($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->getInterfaceNames())) { $klass::staticInit() }
Upvotes: 34
Reputation: 35167
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( /* .... */);
}
}
Upvotes: 10
Reputation: 6341
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.
Upvotes: 3