I am trying to use a variable in an array within my class
class MyClass {
public static $a = "World";
public static $b = array("Hello" => self::$a);
}
This code doesn't work. Should I be using MyClass::$a or something else. Any ideas?
3 Answers
You probably can instatiate them at runtime:
class MyClass {
public static $a;
public static $b;
}
MyClass::$a = "World";
MyClass::$b = [ "Hello" => MyClass::$a ];
Or you can create a static initialization method:
class MyClass {
public static $a;
public static $b;
public static function init(){
static::$a = "World";
static::$b = [ "Hello" => static::$a ];
}
}
MyClass::init();
1 Comment
Jason Lipo
This is very good. It works on what @awlad-liton said, but this approach is more useful - thanks a lot!
If your $a won't change, make it a constant
class MyClass {
const a = "World";
public static $b = array("Hello" => self::a);
}
var_dump(MyClass::$b);
2 Comments
Jason Lipo
Yes, this does work. However in the context I want to use it, I don't want $a to be a constant.
Mark Baker
In that case, if your properties still need to be static, @HAL9000 has provided your options.
class MyClass {
public static $a = "World";
public static $b;
public function __construct(){
self::$b = array("Hello" => self::$a);
}
}
$obj = new MyClass();
4 Comments
Jason Lipo
Yes I think that's the answer. I have to use a
__construct function. Thanks a lot!Mark Baker
Note that if you want $b to automatically reflect any changes made to $a, you'll need to set self::$a by reference
Awlad Liton
@Jason Lipo: You accepted my answer and after that someone edited his answer after acceptance you did change your acceptance also!!
Jason Lipo
I changed the acceptance not because of the edit. I tried the static function approach from @HAL9000 and that proved to work the most simply.
self::$arequires a runtime evaluation. If your $a isn't going to change, make it a constant$bin the class constructor.staticif (!$b) { self::$b = array(...) }.